I have a non immigrant OX for 5 years and in Thailand. I am 63 so not retired but also not working. Retirement visa has less requirements for cash in the Bank.
I have OX and you still end up doing 90 reporting etc but you can open a bank account with it if you have a permanent address (not hotel). Then you should transfer money within 1 year to the account as they like you to report annually. Better to go for a visa that requires the least in a bank account as you don’t really want that much cash tied up doing nothing, especially if the baht weakens.