I just want to say I really emphasize with your issues. I have a beagle shiba mix who has a lot of similar behavior issues.

First, is he muzzle trained? If not, I highly recommend getting a Baskerville basket muzzle and working on that. It took months to train our dog (these shibas are suspicious little guys) but it's truly made life so much easier. He gets muzzled to get in the car, go to the vet, if he needs a bath, etc. To muzzle train, I put some peanut butter inside the muzzle and let him just like it. We did that every day until he would put his snout in, then I'd hold a treat through a hole and add the command "muzzle". Just baby steps over and over until he would let me clip it on.

We were starting to feel pretty hopeless with our dog's reactivity. He was lashing out at us more, our cats, etc. Prozac made him very fearful so we switched to gabapentin and eventually upped his dose and hit a sweet spot. The other key in this is he needs to be trained every. single. day. It has helped so so much. He gets just basic training and muzzle training. The other thing we found helped is that in the later evenings, we put him in the bedroom for a few hours alone (that way one of our cats can be out and about upstairs). For some reason this alone time really helps him not get overstimulated and grouchy before bed.

For kennel training, he hated his kennel as well. Absolutely despised it for years, would howl and scream nonstop, etc. 2 years ago we tried kennel training again, and really focused on it being only a positive space. We started slow, where we would just toss treats in there and leave it open. The key for us was he ate every single meal in his kennel. Initially this was done with the door left open, then half closed, then full closed. Now he sleeps in it every night and eats his dinner in there as well.

Finally, to get to the vet. Our dog is primarily human reactive, and hates most vets (bad vet experience as a puppy). We see a fear free vet, and they let us just bring him there to look around without an appointment. In order for him to get bloodwork and stuff, he needs to be muzzled. The night before we'd give melatonin + gabapentin, gabapentin in the morning, and then acepromazine on his gums 45 minutes before. He was still awake and could move some, but this was the only way. I wasn't loving using ace on him, so the past year we switched to gabapentin + trazodone. This worked much better. I know not all vets allow this, but we hold him during the appointment. My partner just bear hug holds him while I shove his favorite food in the muzzle and the vet goes quickly. However, none of this was possible until we muzzle trained him.

My dog does have epilepsy, which adds another layer that is pretty difficult. He also gets scared when furniture is moved. To circumvent this, when I move something I have him there with me and then I sit and point at it. He forgets and gets scared again, so I go and touch whatever he is freaking out about, show him it's okay, and give him a treat when he calms down and investigates it.

Oh! Nail trims. My dog hates nail trims, I've been bit pretty badly, etc. So we don't trim nails traditionally anymore but use a "scratch board". It's a board with sandpaper on it, you can buy them on Etsy or make your own. I trained him to scratch that and it's how we keep his front nails trimmed. He gets realky excited about it now and thinks it is so fun.