Actually, the diving here in Thailand has been quite good all summer. Just my opinion, but there seems to be more reef fish and pelagic's, in the park areas anyway. There are plenty of operators open now and the local operators are all quite full on the weekends.
Phuket is opening up for the Andaman See area and there are quite a few liveaboard's of all types currently taking reservations. I think the one thing to keep in mind is that most all the boats have schedules BUT they will not go without a certain number of divers. It's best to get on boats that are at least 50% full before you make a reservation.
A couple things you really need to understand before attempting to come here on any type of visa, no matter what you read or hear, it is very difficult/complex to actually get one of these visas and arrive in Thailand. Not a single person has applied for the long term visa they have been offering, its simply too complex. Every day we hear about new schemes being proposed in the PM's weekly meetings, but to date nothing has come of anything.
The other thing to consider is that all of the tourist areas, Pattaya, Samui, Phuket, Krabi etc. are virtually ghost towns, especially through the week, it will not at all be like you might remember it, pre covid.
All that said, there is nowhere in the world I would rather be than here right now, all things considered, life is good....very good.