In my experience, this does work somewhat, but doesn't set up the routes properly[1] and doesn't provide an interface to the networkmanager applet, so you are still left with configuring the profiles in the terminal. There is much left to be desired. Sadly the third-party plugin isn't much better and seems to be discontinued[2].
Interesting. I haven't had that happen because I do split-tunnel, but I will have to keep that in mind in scenarios when I try to forward everything thru the tunnel. All I needed to do for split tunnel was just adjust the route metric. (https://tujun.ga/2020/02/18/wireguard/) Agreed about the lack of GUI though, I do wish there was a GTK applet for it.