There's also https://pangolin.net/ which is kind of similar, and I believe a YC company.
Does that have ties to the US? If so it's not playing in the same ballpark.
US citizens may not be aware, but due to POTUS "made and maintained in Europe" is becoming more and more important to EU.
Not quite similar tho. Pangolin is a reverse proxy, NetBird is p2p mesh for internal resources remote access