What are my options for extending or switching my 1-year O-A visa before it expires in Thailand?

Another option would be for you to look into the LTR (Long Term Residence) Visa for "wealthy pensioners"..

It's offered by the BOI (Board of Investment)

I know many many people who were on O's OA who switched over to this 10 year LTR visa

here's the website for it

You can get a new year of the mandatory 100K USD insurance print out the coverage dates and then BEFORE your OA visa itself expires you can bounce out of thailand and back in to get a new year entry stamp (or as long as your insurance is valid for up to a year).

You might as well get all the time out of the OA you have now before you switch to something else

Now as far as can you apply for the 10 year OX visa, you can but you do that in your country like you did for the OA visa you have.