Been going to Thailand for the past 40 years, they never asked for cash of any currency upon arrival at immigration.
The TM6 form is the arrival/departure card, (given to you on the plane) which foreigners are required to fill out with their passport information and other personal and travel information when entering or leaving Thailand.
itās a tourist Visa but itās called Thailand Visa on Arrival (VOA) which is a tourist visa that will allow you to enter the country as a tourist up to 15 days.š¤Ŗ
they do give tourist Visa on arrival in Thailand, but soon they will implement the ETA visa that you have to get. Right now this has been delayed, no date yet when they will start implementing this.