because you can get a visa exempt stamp on arrival which at present gives you 45 days and then can extend for a further 30 days. I’m not sure what you mean by Thailand is “still” closed?
But if you want to go for 1-2 weeks for surgery this ain’t doable due to the quarantine you will have to do
doesn’t matter if you have no symptoms, you can still have the virus and spread it just as much as if you had symptoms. Home isolation probably wouldn’t work in Thailand as there are too many distractions haha