a) that decision has been made some time ago and zigzagging between ARM and AMD is a sure way to make sure nothing gets ever done for real
b) Linux on rPI/ARM relies on a binary blob for GFX drivers that might not be useable for MorphOS
c) the only ARM HW that is readily available around AMD/Intel performance is the Apple M1/nix/Pro/Max and as much as I would like that idea I somehow doubt it would be feasible