get the debit card if you can. I use it all the time when traveling to different countries. You are able to convert funds within the Wise account and the use the debit card to pay where credit / debit cards are accepted.
BTW In Thailand you will find many smaller places, especially street vendors do not accept credit cards. Cash and Thai banking app are the preferred way to pay
is did this in BKK in March this year and was also required to have the 800k in the bank for the initial 90 day visa. I believe it needs to sit in the bank 60 days prior to applying for the one year extension; so in that case it kinda makes sense to require it at the initial 90 day application.