It's been working well for me as a kind of poor-man's tailscale, connecting several VPS and several laptops.
Though I wonder if the network routing would break down beyond a certain scale, or if it can be resilient against attacks. I don't know enough about the inner workings to be determine the weak points.
Mmh, I heard that one before... It's one of the main points for ipv6 ( ・ั ﹏ ・ั )