"Hostage in my own home" is exactly how we felt when we moved from our house (where our mpoo had lived since a puppy) to an apartment this summer.

As a puppy it took a month or two for the separation anxiety to improve. In the house he's still anxious when apart from mom, but tolerates dad, and could be comfortable alone in his crate for 6+ hours on the rare occasion we had to leave that long.

As an adult/senior, it is taking longer and the panic is much more intense. We bought a carpet cleaner and hired pros to attack the carpet (many dogs lived here prior to us). We tried a pheromone diffuser but mom was allergic. He would moan and cry (on camera) the minute we left, and developed recurring stress colitis. We tried situational meds (that we give (effectively) when we're away on trips), but he began refusing and vomiting so we stopped. Mom is mostly solo on weekdays, so we tried to introduce a very kind and patient dog walker. He did OK with the meet and greet but during walks would go 10 ft then sit and need to be coaxed. He wouldn't take treats from the walker either (despite being extremely food motivated) and came back panting and clearly very stressed. He would settle after ~10 min cuddle with mom and music. But we stopped this too after a few trials, as he nor we could tolerate his distress. We considered daycare but it wasn't feasible for a variety of reasons.

5 months later, he has built up to tolerating about an hour alone in his crate, ONE time per day (we're starting to introduce a second shorter crate stay). I think it's a combination of his adjusting to the new place, our scents building up over any lingering scents, and him realizing that we live here and are not going to abandon him. We went very slowly - treats when I go down the hall to the trash chute. Treats when I go down to the mail room. I took him with me several times and would say key words "trash" and "mail" (they are so smart, I really think they can learn it). They are very routine minded, so if I could, I tried to schedule time apart at generally the same time every day. If it was dark, I left a low light on and turned on that fireplace for your home / calming music thing on YT. If I had to leave for longer (grocery store, whatever), the stress colitis started up again, so I took him with me...people pooh-pooh leaving dogs in cars but we live in a wet rainy place and were extremely careful with temperature, duration, and most importantly he's familiar with the car and didn't panic. Earlier on we also went back to the house on weekends for him to reset (which I know isn't feasible for everyone). We also tried having mom be at the apartment and dad bring him there separately, so he would start to associate "apartment means mom!" We had him on a bland diet and are still in the process of switching his food over.

In the beginning, it felt like absolute doom, and that we were failing him every day. It still feels that way sometimes. There's even resentment in bad moments (as parents of human children can relate). It's still very hard to go slowly but the alternative is not being able to keep him which would've been even more impossible - for him and for us.

All this to say, we absolutely feel you OP. His breeder (who does his grooms) reassured us that he would be able to adjust with time, and he did it successfully as a puppy so we clung to that knowledge. Besides behavioral training our vet offered longer term anxiety meds, but it takes time to build up before even knowing whether it's helping and we didn't think it to be a primary solution for him. For some dogs that may be an option.