Just go to a True store and get the esim only. 50 baht. comes with 1 day usage (I think) then you get the true app connected to it. Recharge within the app heaps of different packages depend on your needs. I believe the sim is valid for 2 years.
Been asked by airlines afew times and I just say I’m happy to take that risk that they might refuse me. They just go on and say it might be very expensive blah blah never been a issue.
They seem to be cracking down on non tourists sims, and require a thai national card to buy them.
But I just went to a dtac/true store ask them for the 50baht esim (they will try selling you tourist packages just say no just esim only) it comes with 1 day unlimited then install the app and you will have heaps of packages to pick from all allot cheaper than the tourist package.
I got the 450 baht unlimited 10mbs data for 30days