I confirm that they are missing on the Baron and the C-172, unlike with AFS2 as mentioned by Armitage
However, there are still some GA models, with either a somewhat basic map or a complete GPS but all functional.
DR-400
Extra330
Pitts14
Tomahawk PA38
Then they also exist on other optional models.
C152
D027
Duchesse76
PA38
Piper III
Piper IV
and Tecnam
However, I don't know why IPACS skipped these two models for FS4?