That SoM is well within KiCAD's capabilities. Layout is not the issue. The fraught part is designing the DDR4 interface -- a pro shop will pay out the nose for

That SoM is well within KiCAD's capabilities. Layout is not the issue. The fraught part is designing the DDR4 interface -- a pro shop will pay out the nose for a signal integrity tool like Hyperlynx to do simulations. While in theory you could write your own sim tool, or somehow respin your way to working boards, I think either approach would be a challenge.