I would like to find COVID insurance for a single day only.

I am planning to go to Phuket by bus next week. As far as I know there is a COVID checkpoint at the entrance to the island. If I catch covid during my trip, I want to avoid paying huge hospital bills myself.

Is it possible to buy one-day COVID insurance now in Thailand?
 

Not available for a single day, and to ensure coverage, you need to sign up at least two weeks before exposure anyway, so you're already late.