Honestly, the "current" method of U-Boot Overlays, that we use for the
am335x family is not usable on the am57xx family (aka BeagleBone AI)..
U-Boot is split in two different blobs, SPL and U-Boot, SPL loads
first inits the ram and loads U-Boot proper.
For the am57xx family, we need to setup the pinmux'ing in SPL, there
are patches/wip's for "SPL Overlays", while that is still in heavy
development mode, some of which has now landed in u-boot git master..
This would be an awesome GSOC project.. I'd estimate it would take a
good working month for someone with no experience with the
am335x/am57xx to get something cool..