In the rule book, page 24, it says "Note: ...A card without an influence value cannot be used with an identity card that has a different faction affiliation."

I'm assuming this applies to most agendas, as they do not have an influence value. I.e.: You cannot play Jinteki's fetal AI agenda in a NBN deck.

Is that correct? Thanks in advance.

That is correct. No out-of-faction agendas.

Yep, you got it in one. We haven't seen any non-agenda cards without an influence value, but the design space is there. Maybe that's what Green needs to keep Yellow from stealing its best cards and doing it better.