Yes, I think this is more or less a direction we want to go. A number of users have expressed confusion by the fact that we separate Favorite POI from Pins. We will likely try to unify them, and add the ability to set a POI category on them. Eventually we would also like to add a service to allow users to contribute POI back into the OSM project, and even to rate/review them (OSM is lacking in this kind of subjective info).
In our coming update we have removed the Favorites screens tabs, replacing them instead by a drop down menu to change the view, with an added default view of “All Favorites”. I imagine we could add other automatically organized views in a later release, for example, to browse “All Favorites by Location” or “All POI/Pins by Category”.
I really like the idea of being able to assign POI categories to Pins, and to show them with these icons on the map. We will probably also craft our own set of POI icons on the map to match the POI Categories too, but as there are around 150 POI icons, this is a lot of graphics design work to do. Note that the current version of PocketEarth does allow you to customize the Pin icon already, by choosing from 10 icons and 10 different colors (Go to Pin Detail screen, tap Edit, and scroll to the bottom).
BTW, our Nearby Categories do *not* come from OSM. OSM has a somewhat unfriendly freeform POI tagging system, so we and most other OSM apps create our own categorization scheme and map OSM POI objects into it. Also for displaying the info about a POI, we reprocess the OSM tags in order to present it to the user in a more concise and easier to understand way. Also so that we can localize it to the different languages that our app supports.