The footprint ribbon dude is in the Hotel Grand Resort. The big building beside where you do the Pyukumuku chucking.I have two questions:
1) Yesterday, I got a very obviously hacked Crabrawler, but that's not the matter. The matter is one of the ribbons it had - it was a Footprint Ribbon. Does the NPC that hands out that Ribbon even exist in Sun and Moon? I don't remember having seen that one.
2) Is it even worth purchasing one of the Gen VI games given the Pokebank update is close? Or there is nothing worth getting there that I could not simply get on a Wonder Trade or GTS?
Depends on what you want from them. They're decent games like any other Pokémon. It's very much worth noting though that due to Bank they're the only Pokémon games not needed in a transfer chain; you can transfer right from Gen 5 to Gen 7 without needing Gen 6.