@Stewart **************
as you have been living in Thailand for several years now be prepared if asked by Thai immigration why you do not have the correct visa for living in Thailand?
As you state you are now on a Non O visa that is ending soon....
If it is a Non O Volunteer Visa you must first get a letter from the NGO who sponsored you for the Non O visa and take it to the Thai Immigration office where the stamp was issued to request that they cancel your volunteer visa.
The Thai Immigration office where you are really living now will not accept your COVID extension application ...they will tell you to first go to the immigration office which issued the Non O visa stamp now in your passport to cancel the Non O visa.