I've no idea about pockets but revolut is not universally recognised as a bank so whether its accepted or not will likely depend on where you apply and where you apply from
How long ago was ownership of the Thai company transferred? When did you cancel your Non-B and work permit? What did you show for your source of income and did it reference the Thai company at all?
Things are getting tighter so you really need to sign up for a course that's a minimum of 6 months, preferably a bit longer. 6 weeks of dental treatment can be done under a visa exempt entry, they're not going to give you a DTV based on that
It's very difficult to open a bank account on a DTV although not impossible. All you can do is go from branch to branch of every bank and hope you find one that will. You'll also need a residence certificate from immigration