@Ellie ******
great question. I’m not sure. That’s why the op should contact the immigration office.
If a “non-b visa” is a one year extension of stay based on employment, which got canceled, I know some immigration offices should allow a conversion to be done to an extension of stay based on marriage.
Getting a non-o based on marriage inside Thailand, it’s one I never heard of before.
But... the immigration office would be the one who would know for sure.