Thailand is technically open to visitors, but even with a negative Covid test there’s a 14 day quarantine requirement and the idea of being stuck inside a hotel room that long hasn’t been popular. It’s attracted only a few hundred tourists per month to the country.
However people will go to greater lengths to visit friends and relatives than they will for just a vacation long enough to justify the quarantine period. I saw on social media that the owner of my favorite Thai restaurant was back in Bangkok, in the middle of his quarantine period at a hotel with his wife. He was gracious enough to share his story and some photos.