Yes, you can use it to add/remove nodes. I have tried it once when I noticed it and seemed to work fine and is quite convenient VS having to stop the service and unplugging my zwave stick to use the button.
From memory I just hit the “Call Service” button and performed the include action on the device I wanted to add and it just worked.
I used that function yesterday. I hit add node then the action button on my plug and there it was. If you run that process and you don’t see your node try restarting hass. I had to do that to see the plug.