> Another similar solution which is production ready is ZeroTier. That one supports IPv4 on your private network as well.

With a centralized server and usage limits and depending on proprietary software. No, thanks.

Once 2.0 comes out, the centralised root will go away.

But even now you don't have to use the project's infra. Private roots are possible if you want to be independent: https://docs.zerotier.com/zerotier/moons/

You can run your own infra completely independent of them.

Also, their approach is to decentralize until it hurts, then centralize until it works. Calling it centralized is a bit of a stretch.