it would be good that in the next release add something like p2p=all-p2p / queue-p2p / only-drop-p2p for firewall mangle

then one could drop all p2p that cannot be queue and queue all p2p that can be queue

can you include this in 2.9.26?

mangle marks packets, it does not drop them!!! dropping and queuing you can already do in the appropriate sections - firewall and queue.