What should I know about transitioning from a COVID extension to a Non-B visa in Thailand?

whether you can go from a Non-B that went to covid extensions to ANYTHING else (seeing as you can't get another covid extension AT ALL) is between you, your employer and the immigration office you deal with.

SO

what you should do is get someone from your employer and slog on out to your immigration office to find out if you even would be able to get anything employment related inside the country without having to exit/re-enter, wipe the slate clean and start over from square one.

Believe me this answer isn't a cop out a LOT comes down to the ability of your future employer to meet the requirements AND whether your immigration office will or won't do it.

3. the visa of course must be issued, not just applied for

2, no one know, but you are not eligible for another one as you have had a non b

1, as quick as your employer can arrange the paperwork