On the subject of desktop messaging: what are the decent alternatives to Google Messages for RCS/SMS on Android? I want to be able to chat on desktop Linux (preferably not in a Web browser) in a way that syncs with chat on the phone. I'd rather not give up RCS, and messages should be secure in transit. (There's a BitlBee plugin, but it transmits messages over the network in the clear.)

My best guess is that this isn't actually possible. (But what does postmarketOS do?)