Let me know what platform you use for encrypted video calls that isn’t based on trusting a third party with the private keys.
That is usually the requirement to get a UX people will use with their non technical family, but people accepted it, I think in part because it didn’t seem practical to index it all. It definitely is practical now though.
Not the GP, but I'd at least imagine that a self-hosted XMPP could get the job done. You'd probably also need your own STUN and TURN servers, but it should definitely be doable.
Hell, might even be doable with public XMPP and OMEMO, but I don't know if that works with the video call stuff.
It's sadly a lot of effort, but I feel that for stuff like family privacy stuff, it might just be worth it.
I self host prosody (an XMPP server) with a TURN server in my living room. With Guix System this is largely declarative, aside from the DNS records and initial user account registration (which I do on the command line).
We're using it for messaging, sharing files, video calls across continents, etc. Re video calls: the XMPP and TURN servers are only used for negotiating the connection, so you don't need a very powerful machine for any of this.
This makes sense because the only thing you can encrypt is text and not video