Unfortunately I don't have anyone who can help me; Gen and I live with roommates who aren't nearly comfortable enough to help hold an agitated cat, and they're both away this week in any case. And my boy is definitely what you might call difficult; really I think of it as being very independent and valuing his bodily autonomy, but it's been giving me no end of trouble as I try to care for him recently. I've tried dosing him with gabapentin before for car rides, but he refused to eat the food I mixed it into, refused the pill pockets after the first time I gave them to him (this was before re-diagnosis, I don't know if they're safe now anyway), and the one tried I tried to dose him with an antibiotic with an oral syringe, he acted like he was being murdered just when I tried to get the tip in. (I'd say this was because he's probably sore from periodontal disease, but he rubs the side of his face hard on the edge of my laptop all the time, etc.) And "acting like he's being murdered" (aggressive panic, yelling, flailing, scratching, fleeing) is how he has always reacted to attempts at home blood tests, which, since I can't restrain him effectively on my own and also do the testing has made it a futile, demoralizing, painful experience for both of us. I don't think I ever actually managed to get a successful reading with a BGM, not once.
I feel like I'm all tales of woe lately. I love my cat so much, he is a sweetheart and a snuggler and endearingly demanding, but he's just heartbreakingly resistant to all my efforts to help him. :/ The one thing that goes easy, thankfully, is administering the insulin itself. He'll often make a complaining noise and act all startled and affronted briefly when I do it, but it's a token display at most and he doesn't always even bother. I think it helps that it's really fast.
Oh, Allie, I really feel for you. Staci can vouch for this because she was there to see it all happening, but pretty much every single problem you're having, I also had. Down to not being able to get him to eat food with Gabapentin in it, and oral syringe meds somehow being the
literal worst thing that ever happened to him, etc. That last one wasn't even that long ago, just a couple months. Getting meds into him has been a struggle forever and we've tried so many different methods, which gets expensive.
At least in regards to that specific thing: the one I'm finally able to get him to eat is a chicken-flavored liquid mixed into strongly-flavored food. Admittedly, though, he's on an appetite stimulant and I've timed it to make sure he's fairly hungry at the time I have to give it. (On that note, if you ever try a flavored liquid, be sure to request it be sugar free! Apparently they're sweetened.)
Transdermal gabapentin is a thing; it's not cheap because it's compounded, and IMO it didn't seem very effective for us, but if literally nothing else works it may be worth trying.
Has he been fully checked out for the dental issues? My guy got 8 teeth extracted in September and he used to rub his cheek/jaw hard against sharp/hard surfaces like that too (so I wouldn't take it to mean that it doesn't hurt). My theory is that pressing eases the pain a little bit. It was actually after the dental that we had to give the oral syringe meds and it was so traumatic for all of us that even my partner was crying. Absolutely awful and will never do that again.
If it makes you feel any better, I have never gotten a single manual reading either. Not one. My partner got exactly one and that's it. I know that all the stickies say that every cat eventually gets used to it and it doesn't hurt but unfortunately that's absolutely not true for all cats. Maybe we're in the minority, but mine never got used to it, it was always clearly painful and never resulted in a usable result after all the suffering. Practice and time didn't help for us. It's important so if you're at all able to I'd still encourage you to practice in case it does get better for you, but please know that if it doesn't you're not alone. I know I may get looked down on for it, but until everyone who insists that it works for all cats has to do it for mine every day, they can think what they want. I'll do what works for us.
My guy is also the sweetest, snuggliest guy little thing but so resistant to help, even when it's not painful or scary, etc. It's so hard when we can't explain what's wrong or that we're trying to help. (Not trying to make it about me when I compare, but expressing that it seems like our situations are very similar!)
I will say that while we still struggle a lot (Xander has multiple issues whose treatments contradict each other and that I'm still trying to learn about. That's on top of already being difficult in general to do things that other people's cats take calmly.) that it really does get better. Maybe not everything all at once. But at some point you'll realize "Hey, this specific thing is so much easier than it used to be." For the longest time injections themselves were the hardest part. He's so sensitive and afraid that we use the gabapentin and I have to numb him with lidocaine on top of the normal "distract with a treat" thing. It felt like it took forever, but somehow the thing that caused me constant anxiety and dread and that I shook like a leaf while doing every single time... Became like the easiest part of this. Which is mind-blowing to me. This specific part of the process made me think I could never do this and I literally spent 90% of my time crying. And now that thing is the "no big deal" part.

I know it's not as great as answer as "this whole thing will eventually be easy" like it is for some people, but I got it gives you
some hope. I never imagined getting to this point and I still did.
The Libre seems to be reading again now, but given the way things have been going for the last maybe 14-16 hours, I'm not super confident. Plus I have to go back to the office on Monday which is going to be hard enough (being away from him, and also my boss is kind of a jerk and she was awful about me needing to work extra remote days to care for him earlier this week, and I'm dreading dealing with her). I want consistency.
This sensor worked great for the first 3.5 days. It was attached with surgical glue unfortunately (done before I had a chance to say anything, though I've since spoken with my vet about it and if we do another application at the office, we should be good). If it didn't interfere at first, does it make sense that it would be now? Also I have Gen wearing a t-shirt to protect the sensor, but he does groom over it, so I imagine it could have been jarred over time. Not sure what to do about that.
I do have a spare (only one as it cost me $89 since the pharmacist couldn't make the coupon work, and he really did seem invested in trying so IDK), and I have coconut oil. The trimmer I ordered and the Skin-Tac wipes arrived last night, though I haven't opened them yet. I guess I could just bite the bullet and give it a try. I'm so nervous that it will be another disaster.

I wish I had someone who could help.
Gosh do I look forward to a day when I can post here and it won't be a litany of troubles!
The question of reliability is really hard, and even more so when you can't be home! I wish I could say it'll always be reliable but unfortunately while our experience has improved greatly over time, they can still occasionally be pains. I'm sorry that you have to deal with an unemphatic boss on top of it!

That certainly doesn't make anything easier.
Do you have Costco nearby? I get mine for ~$33/each there. You don't even need a membership to use their pharmacy (though you'll get better discounts if you do!) it's not as cheap as the $19.99 coupon but it's possible they'll take that too. I also tried getting it elsewhere and it cost $90/each which was ridiculous. They're expensive enough as it is! That's absolutely an understandable reason to only have one extra on hand, but if you're at all able to go somewhere cheaper like Costco and get a handful, I'd highly recommend it. Having backups is especially important in the beginning of applying yourself, because unless you're way luckier than me, there will unfortunately be failures in there.

I completely understand budgetary considerations though, it's not possible for everyone. Sucks that the Libre is the only option for some of us because it's not cheap, especially while learning.
I wish you had someone to help you too! I couldn't do the Libre changes at all without my partner. Staci is incredible and manages it but I didn't know how. I'd love to see a video lol It's too bad we don't all live near each other and could help with things like Libre changes. That'd be awesome.
I also look forward to a day when I can post without a litany of troubles lol You are absolutely not alone. I know some CGs seem to have such a smooth go of it (which is great, of course!) but unfortunately some of us, like me, are always struggling with something or other. The upside is the forum is the only place with people who can possibly relate or understand.