From my understanding with the TER scoring system…

The only way to get a 10 in performance is to offer anal. It should be easy to spot. Look 👀 at performance 10 & their TER profile will state anal. I did not start offering Greek until recently it was an exit only for so long lol 😆 Smile for me!

If a provider is truly bi she can get a 10 without anal.

Have you considered seeing touring companions?  I just checked out the Portland "Buzzz" board and saw names of two companions that offer Greek. One I've seen and the other I hope to see, at some point.  Just a thought.