Nothing new about this. If you come to Thailand with no visa, you get 30 day (depending on your nationality) and you can get covid extension with that. You probably need to get 30 days extension first.
Thai pass have nothing to do with the visa. If you plan to stay 45 days, you can come with no visa and you get 30 days and you can extend 30 more days in immigration.
For the students visa, you can do pretty much everything. Cooking, learning Thai, yoga... But a lot of people abused the system and now they check if people are really doing the courses.