Thank you for the very thorough reply, especially the terminology. Yes, I think what I want is site-to-site vpn hardware to have lan parties with my family on consoles that don't do well with the internet (I'm looking at you nintendo switch).
> It looks like they have a crowdfunding campaign to launch a site-site vpn device
that is what i meant with the appliance.
I can't speak from experience, but what i've read yesterday makes the previously linked comment the most interesting [0]
the edge router costs ~$100 and has enterprise hardware. The only missing feature is the management frontend, which isn't stricly necessary. And the referenced vyatta-wireguard [1] has a code excerpt which looks like a site-to-site vpn
So multiple people have listed ZeroTier, and you mentioned it as a client-client. It looks like they have a crowdfunding campaign to launch a site-site vpn device... I think: https://www.indiegogo.com/projects/zerotier-edge-open-source...
Edit: Thank you so much for teaching me to fish (the terminology) instead of just giving me a fish (recommendation).