Not sure if applicable to you. I have done this inside Thailand: Non-imm "B" (initial 90 days stamp, not extension) - amnesty - Covid extension (multiple) - marriage to foreigner with work extension.
I used to work for an internship agency. Interns can come on ED visas too, if they can get a letter from the university, stating they are students, internship position, period etc. Then they don't need WP and can extend the visa with the same letter. (This is what I remember, I wasn't responsible for visa).
Add: Ah! It needs to be unpaid internship. Paid internship requires Non-B and WP as stated above.
I went to CW to get the same stamp yesterday. Immigration officer told me that if I come end of next week, they MIGHT start stamping until end of December. But I wanted to get the stamp anyway so got until 30 Nov.
only allowed in via repatriation flights. There's a very few ones and long list of people. So they are giving priority to elderly, families with young kids, sick people etc. Which I am not. So I won't get on a flight for months. There's been protests and anger from the community abroad, no results yet.