I'm sure there's some technical reason Apple could not / did not want to make Pencil 2 compatible with the M4 iPad Pro.
Undoubtedly, many will exclaim, "corporate greed" or "apple tax" but if we're in a position to turn in our older iPads and buy the latest but our line in the sand is the accessories, I think we're doing OK.
But, It looks like Apple is only looking for new entrants into the iPad market or those who are handing their current device and accessories over to someone else, then buying a whole new set and not those of us who want to simply lift and replace our current iPad for the new M4.
Oh, well. It's not like my current M1 iPad Pro is any slouch. Onwards.