Just read a report about this from someone in late oct having done in Phuket-staying there in the sandbox scheme.
It is for now still an extra 60 days (thanks covid) in lieu of the normal 30-as long as this lasts. There was NO request to see the costly sickness insurance-so the one you have already with world wide cover, but without that nasty written rule that it is for 50k (or what is may be) $$ is enough. But of course there is no garantee whatsoever that other offices follow same lax rules. They even described it as a faily pleasant experience (as such not that uncommon for most Thai encounters out of officialdom)