For Unity App you must go through the App42 Backend it’s provide your all feature requests. Like if your app user’s want to create custom characters you will like to use App42 Avatar Service.
And also allow other players to view other player’s characters and be able to comment by Review Rating Service
Photon is for realtime game play and doesn’t aim to solve the problems you have listed. You need a backend (either your own or App42) to build the user character and store the likes/comments.
If you don’t need interaction of players, then Photon is most likely not the right tool. Like Maxim, I would point you to php or something and some DB.