My contract was not renewed after over a decade working for same employer. 

I cannot switch to a retirement visa at this time. Am I grandfathered in under the automatic COVID extension until July 31st?

 

A doctor has suggested surgery once COVID settles down, supposed to see him in July. Is it possible to switch inside Thailand to 60 day visa for medical reasons? Usually it seems people apply from outside Thailand for this visa and then extend at immigration if needed.

You can stay until July 31st under the amnesty.

After that if you needed to stay for medical care and have the supporting documents for an extension you could get up to a 90 days. The documents from your doctor and/or hospital must state you are unable to travel.