In regards to what to map to the pen and tablet buttons – I suppose the button mapping depends what you’re using the pen and tablet for, whether it’s sculpting or texture painting etc. They’ve got rather specific functions in their respective workflows that might not be used elsewhere as often.
Perhaps instead consider what hotkeys or functions that you would use throughout blender as a whole to assign. For me personally, my favourite functions that I’ve got mapped to my pen and also the side buttons on my mouse are to swap in and out of local view, and also frame selected. I’ve been using my pen for texture painting lately, and being able to jump in and out of local view (NumpadSlash) to see my painting in perspective of the other objects has been great. And being able to quickly frame selected objects (Numpad Period) has been a life saver when rotating and panning the viewport to such an extent that I get virtual vertigo. Preferences like these that can be used throughout blender are what I’m talking about!
That being said, Quick Favourites is a more contextual based option to keep in mind!
