an alternative is also the https://librem.one/ services run by Purism. VPN, Email and more. All server and client code is at source.puri.sm and it's mostly only rebranded "standard tools".
agreed. I recently removed Signal and started using xmpp (again). It'll always be there (Signal probably won't) and getting a friend to install conversations.im and register a name on a public server is not much harder than getting someone to install Signal. To me it somehow feels like it's a good time for xmpp