that is not exactly true. Crypto is regulated as "digital assets" under the Royal Decree on Digital Asset Business. Trading, buying, and selling cryptocurrencies are permitted, but certain activities, such as using them as a means of payment, are restricted.
actually I never carry cash anymore. At least not in BKK. Maybe in other cities there can be outages. For me it’s 90% mobile (prompt pay and apps) and 10% or less card. No more piles of unused coins, grimy notes, etc….
You can donut from 3 days before travel until day of travel. If you haven’t done it before travel it can be done from a smartphone in the airport. You receive immediate confirmation