@yasmin_bree
I'm surprised by some of the unenthusiastic (even outright negative) responses you've received to your post,
I think Bulgarian immigration would welcome an American with a full disability pension. It seems unlikely that it's less than the typical Bulgarian pension, and most likely even exceeds the minimum wage ($650/m in 2025, due to be $730/m in 2026).
Bulgaria has its problems, of course, but "quieter and less stressful" (and cheaper) than America is mostly likely fairly easily achievable.
As a vet, I'd guess you're entitled to some kind of free/inexpensive health care, and you might not be happy to lose this. In Bulgaria, you'd need a private healthcare policy. It's a lot cheaper than USA, but probably worth getting some quotes. As a non-EU citizen, you can't qualify for public healthcare until 5 years of residence (as a pensioner). If you're doing some kind of online biz, you could qualify earlier by registering as self -employed.
5 years of Bulgarian private health insurance isn't going to be a huge cost, and it's balanced by your access to the public system after 5 years (voluntary contributions as a pensioner/non-worker are about $25/m, a fairly trivial sum. I pay this myself, but I've not yet been to a public hospital as most private hospitals get reimbursed by NHIF too (and I just pay a small private surcharge of a few bucks).
The disability commission mentioned in another post is TELK. I did this for my father, and it wasn't a big deal. If America thinks you're 100% disabled, the same medical evidence will almost certainly convince TELK. I'm not sure the decision is super helpful, but there is a small (teeny) Bulgarian disability pension so you might want that.
Like others, I'd recommend you go for an apartment in a larger city, rather than a village house. But it very much depends on your budget. We're in Plovdiv and it's a great little city (former European Capital of Culture and Bulgaria's 2nd largest city). I highly recommend it as it has all city amenities including many hospitals, several lovely parks, and plenty of downtown sights/activities. I lived in Boston, Chicago, and San Francisco which are great cities. Plovdiv's a dinky, tatty country cousin in comparison... but it's much more livable and much affordable. We have a beautiful apartment next to a mall, large supermarket, and 3 of the main parks... probably for the cost of a shoebox in those other cities. :-)