This isn't a very nice comment (from my reading anyway).
> Be kind. Don't be snarky. Have curious conversation; don't cross-examine. Please don't fulminate. Please don't sneer, including at the rest of the community.
> Comments should get more thoughtful and substantive, not less, as a topic gets more divisive.
I'd love to try headscale, but a bit of research shows that the tailscale macOS client requires a CLI param to connect to a custom server, registry keys for Windows, Android client requires custom compile, and there's no iOS client at all.
Unfortunately if I need to bring anyone into my mesh network who is non technical, this is now a non starter.
I live outside the US and use SMS daily to communicate. Of the ones you mentioned, the only other one I see people using is Instagramm (Facebook messenger).
As an alternative viewpoint, I also have a Tesla and a "normal" car, and I don't find the Tesla requires any "special training" or is objectively worse.
Things are in different places in different cars. Switching keyboard layouts would be significantly more complex.