For Tailscale, there are a lot of posts about how to set up an exit node with a commercial VPN provider.
With Netbird how would one do this? Does it require any extra configuration beyond the existing exit node documentation or will it just work? I did not see any posts about this.
I don’t recall there (currently) being a documentation about it from the top of my head. However, you could make this in the Tips and Guides section if that interests you. My best guess is that you configure a exit node and have a VPN that routes all/netbird’s traffic through the VPN.