I have the Phigolf device. I run WGT on my Galaxy S8+ and use a USB-C to HDMI cable to connect to my 55" TV. Looks great!
Regarding the Phigolf play - full swings are OK, but putting is very far off. Using a putting stroke, that in real life would produce a 10 foot putt on a level surface, sends the ball like 80 feet in the game. So, I have to mentally convert the putt distances - if the game says the putt is 25 feet, I reduce it to about 5 feet and use a putting stroke that matches that. That gets me pretty close.
The swing stick constantly wants to reset for a shot, so if you have to make aiming changes or something like that on your mobile device, you have to kind of swing the thing around so it won't be stable enough to reset for a shot. I wish it wouldn't do that. Once it resets and is ready to swing, I haven't really figured out how to reliably "un-reset" it so I can actually get ready for the shot and not accidentally make it swing.
Has anyone figured out how to play on WGT so that multiple players can play locally using one Phigolf device? So far, all I've seen on WGT is internet multiplayer.