Thanks for clarifying that :)

The client is not, no. Wireguard is open source and you can selfhost headscale, which is an open source server for tailscale, provided by tailscale themselves.

To be clear: I too am using tailscale for its convenience and reliability. While I havent had any issues with wireguard clients, it is interesting to see that there may be cases where switching from wireguard to tailscale can actually still make sense.

Oh, that is crazy! I think I should do a bit of performance testing then :)

Not really, no. Tailscale uses wireguard under the hood. It has a nice user interface and makes setting up a split VPN super easy. It also provides relatively easy ways to do ACL between devices. If you already got wireguard set up, you can skip tailscale.