There's also https://pangolin.net/ which is kind of similar, and I believe a YC company.
US citizens may not be aware, but due to POTUS "made and maintained in Europe" is becoming more and more important to EU.
For a Tailscale migration, NetBird is the direct swap. Pangolin won't give you device-to-device connectivity.
On EU sovereignty: NetBird is Germany-based and explicitly positions itself as a European alternative. Self-hosted gives full control with no callbacks to their servers. Pangolin is US/YC-backed, so while self-hosting gives you control of the data plane, the project itself is American.
Also, NetBird has a reverse proxy feature coming this quarter, which would cover the Pangolin use case within the same platform.
Pangolin is a hub-and-spoke style network. They actually have some comparisons between Netbird and Pangolin https://pangolin.net/blog/posts/pangolin-v-netbird and Pangolin and Tailscale https://pangolin.net/blog/posts/pangolin-v-tailscale