Game data sync with server

Hi, I would like to ask a question and hope any professional and experience people can give me a direction and tip.

I have a project underdevelopment and project has in game store, one of game's feature is able to sync player's item, currency and anything they have bought into server and retrieve those data at any time no matter what happen to player's device.

Due to that feature I research in internet and found Google Game Play Service, I was intended to use it as cloud server until my boss find out that Google Game Play Service required player to login with account and he say no to me, he wants the game to be played without letting player to login and still can sync player's data with server. The reason for that is login popup annoyed player and we already have a Facebook login.

I am out of option now and I think last option is to roll our own server which me and my co-work has no experience on this.

So can any pro and experience expert give me a direction how am I going to do this?

PS: If we decide to roll our own server, can I automatically create an account for player without app been rejected by Apple?