Yes, and it may be a good idea to have it just in case. But the courts in the US so far mostly ruled that police forcing you to give biometrics to unlock is fine, as it is the same as fingerprinting you when you are arrested. But forcing you to give pin/password is the same as testifying against yourself, which is against the 5th amendment. So they usually can’t make you to give them a pin/password. At least in theory. Still better to have it in practice.
In XMPP, e2e encryption (just like everything else) is an optional extension. So in practice half the clients don’t support e2ee, half support different version of e2ee (can’t talk to each other) and pretty much all e2ee are likely full of holes since there are too many implementations to review.
In Matrix, e2ee is in a library that all clients can use, so while it is not Signal, it provides decent security.