I have my home number as eSIM then i can use a sim in the sim tray from any country i visit.
You can get eSIM at airport on arrival and they will set it up for you if you want a thai eSIM. Obviously your phone must be eSIM compatible most are nowadays but still some are not.
As Stuart said no Max, I brought in $50k aud and declared it. I also carried proof of withdrawal from my Australian bank to avoid money laundering questions.