I personally think the collectathon platformer format is perfect for a Pokemon Go style game. Just put all the collectibles one world would have in each predetermined chunk of land. Put the quills in minor shops, pagies in modern landmarks, ghost writers at historical landmarks and so on and so forth. It could also implement the systems described in these videos:
https://www.youtube.com/watch?v=E_uxPnDB2qQ
https://www.youtube.com/watch?v=UDtlizfYPUM