Comment by clpwn

While not apples-to-apples and less polished, we're slowly building up https://github.com/tonarino/innernet as a fully open-source (and self-hosted) alternative to things like Tailscale. It controls vanilla WireGuard under the hood (kernel or userspace implementations), and is lower level (no graphical interfaces yet), though, but depending on your needs it might still fit :).