Final Fantasy is like Black Mirror, there are common themes, plot points, and names that persist throughout the series. However no two numbered titles share the same worldbuilding, lore, and characters.
It's like what happened with Quake I-IV but on steroids. Very different games held together by a promise of what emotions you'd expect.
Both Bluetooth and BLE are perfectly fine protocols. You won't be able to design much for short distance with that much power savings otherwise. The main issue is that for any protocols like this you would most likely need to put it in the 2.4ghz unlicensed band. And that's predominantly used by wifi these days.