Awesome I am looking to do this (run um2+ with klipper).
I am struggling to find a config to use as a base for my setup. I am having issues with my um2 board randomly doing stuff mid print so I think something on my board is knackered, and want to try moving all the processing off on to a raspberry pi to see if it makes a difference. If it is broken I think will just update with a bigtreetech board. I recently upgraded my cr-10 with one and it is a beast now.
Could you possibly share your um2+ printer config with us please? That would be a great start for me.