So the overstay was paid for and cleared up and subsequently you obtained covid extensions.
No problem there.
Next step is that you want to obtain a non O retirement.
I would consider you quickly talk with your immigration office and discuss the requirements and possibility of obtaining the non O.
If they advise you to exit country and reenter, I would consider a border bounce to Nong Kai. Flights to Udon Thani make that an easy trip.
Depends where you are located.
Be aware that a visa exempt entry from Oct 1 is 45 days.
To apply for the non O retirement you would require 800k in bank on the day you apply and 15 days remaining on you current permission of stay.
That's why I suggest you seek clarification from your immigration office.
They all have their own quirks.