@Sarah *******
One document you may be asked for (and I know for a fact Nakhom Pathom asks for it) is a letter from your embassy saying you can not return, OR;
a print out from your embassy website saying they don’t issue the letters, OR;
a print out of a letter from the embassy saying they don't issue those letters.
(Note the "ORs")
If you are American, print this out along with the other documents for your 60 day extension of stay based on unable to travel due to COVID-19; you may be asked for it.