@Cady *****
okay this is how it is, you are correct you cannot get a a 60 day covid extension if you entered on a Visa On Arrival (TR-15)
BUT
IF you can get the letter from your embassy you can go apply for a 30 day extension based on embassy request. It's NOT a covid extension it's given for a different reason.
That's your only option other than taking that extension denied 7 day stamp to get out of thailand in a week.
Remember though, even with the embassy letter the immigration office does not have to give you that 30 day extension. There are reports of people with that letter who were denied.
All you can do is try.