Reading/Writing to a file on Mobile devices using blueprints?

I’m wanting to do a basic turn based strategy game and wanted to get some advise before I started out. Think like Civ but limited to just building armies and cities are the only locations those armies can go.

I feel my game would fit best on mobile and I’d like to make it multiplayer. My thought was, I can write a file that has all the necessary player action information(like what points they control, where their armies are headed, etc) to a file, have that file read by the host device, on a server, and have it update the game state and send it back out, once per turn. On PC this seems pretty straight forward but I’m not finding a ton of info that relates to doing this on mobile devices.

Or am I going about this wrong and is there a better way to do it?

for further context, my background is as an artist but I have put a few point and click style games together in blueprint.