The output for the P4 is 720p, like the P3 A&Ps. Buying a goggle that handles 1080p like the $500 Glyph is a waste of money unless you plan to upgrade your Phantom at some point. The P4 Pro puts out 1080p, so the Eachine Goggles Two priced at $140 is a seriously good deal when compared to the Glyph.
For a 720p output, the HeadPlay HD at $250 was a really good goggle, but, I do not know if they make them anymore. The best the Fat Shark goggles can put out is 800 X 600 and it is not even p although they do try to make you think it does. Fat Shark goggles have terrible resolution but they have no lag time so it makes them great for racing, which is why they are popular.
The 720p goggles, and Fat Sharks, have the benefit that you do not have to see clearly and so you do not have to wear glasses to use them. But, if you should go the route of 1080p goggles, it is 20X20 vision and you will have to wear glasses to see correctly with whatever goggles you choose, if you use reading glasses.
Please do realize that this is all new technology and new discoveries are made daily. This is the latest I have learned.
Aloha and Drone On!