In addition to the FEP process itself arises the question: How to find out what FEP’s an implementation complies to?
I suggest that - for now - this should be in the FEDERATION.md document, proposed last year by @darius in Documenting federation behavior in a semi-standard way? proposed the FEDERATION.md convention, and discussed in SocialCG 2020-02-08.
How this works should be documented in the FEP process too, imho.
Note, I have proposed an extension to FEDERATION.md and will continue discussion in: Improvement to FEDERATION.md convention: Murmurations