Transdenominational/Non-Denominational Synagogues and Rabbis

I just heard about these types of Synagogues and Rabbis from a friend and I wonder if these are valid for marriages, convertsions, and other life matters if they aren’t affiliated with any recognized Jewish movement/organization?

I only know of Orthodox, Conservative, and Reform Synagogues/Rabbis.

I’m in the US and a friend has started going to a Transdenominational Synagogue recently that has a Rabbi that went to a Jewish Non-denominational Seminary in order to be ordained: Academy for Jewish Religion California (AJRCA)