Can I Apply for a Non-O Visa Without Leaving Thailand After My O-A Visa Expires?

I am here on an extension based on an O-A visa. I will need to show my insurance this November when I apply again. I have Pacific Cross insurance with a large deductible. I like the terms of the insurance and it is slightly cheaper than my US insurance was. Getting Thai insurance can make sense and not be too expensive. I understand that it is an additional expense for many people from other countries. You might want to do this for one year only until borders open to allow you do get a non-O at a later time.

Buy an insurance with a large deductible amount. That way you're covered for a catastrophe and you're only paying a few dollars a week. Much cheaper than flying out/flying in, having to get covid insurance anyway and 14 days quarantine! But each to their own I guess

If you are married to a Thai you can apply for a 1 year extension based on marriage. No insurance required.

What about applying for an extension of stay for one year, Robert ?

You have to leave the country to apply for a new visa.