I don't use Godot, but I have tried this method of multi-player before. You will want to use the Steam API, as that will allow for features such as invite to game, but you won't have to worry about port forwarding and such. You can also use it to setup a lobby system so random people can join random people's games if that's what you need. You should use dedicated servers, though, if the game is competitive because the host might have an advantage due to lag. Hope this helps :D