PGP has a bunch of limits (and I’m saying that as a cryptography nerd). We’ve learned a lot of things since the 90’s and the better solutions are specialized protocols like MLS / Matrix (E2EE group messaging) and running all kinds of protocols on top.

The portable identity part of PGP can be handled by something like DID documents which works more like Keybase used to do (depending on specific implementation) where your declare a list of supported protocols with public keys and accounts under your control, so people can still achieve the same effect of using a strong cryptographic identifier to communicate with you, but with forward secrecy supported by default and much lower risk of stuff like sidechannel attacks.