Element has forward secrecy, it’s just that technically with a backup passphrase you’re able to restore your session keys.
If you chose to use no backup and you chose not to export your session keys I don’t see how that would be different. Olm is actually very similar to the Signal Protocol.
I wouldn’t do that until MLS is more mainstream because for large rooms in any messenger you’re always going to have issues with E2EE. We do have that requirement for 1:1 or “private” chats as it is assumed if something is private it’s meant to be private from anyone as opposed to public rooms that anyone can join.
One of the main concerns I have with session is actual general activity within the project. It does seem things have dropped off
Then of course a while ago there was this article which brought up some questionable points about the cryptography in general.
As far as Loki (and dVPNs) go I’ve never been a fan of these networks, they normally never have enough nodes to actually be seriously anonymous.