Power Spots may have different criteria, as many are imports from a 3rd party. You may want to read the clarification discussion, as staff addressed this.
Also, PoGo and Niantic don’t determine S2 cells. PoGo Hub has laid out how these work, and the cells have been around since 2005, way before any Niantic game came about. You can read up on them here.
I myself have nominated many Wayspots that haven’t showed up in either PoGo or Ingress, as they don’t meet the inclusion rules for either game. Ingress uses a 20 meter rule, so if there are other Wayspots within a 20 m radius of a current portal, it may not get added to Ingress.