Well, they will tell us at release. Likely B450, B550, X470, X570 as a first guess after some BIOS updates.
High end motherboards come with more I/O typically.
Additional M.2 slots, more SATA ports, more and faster USB ports (Type-C, Gen 3.2 x2, etc). For AMD the X470 and X570 chipsets support PCIe 4.0, B550 only on the CPU connected slots, and only PCIe 3.0 on B450.
Better sound chips, faster networking, overclocking tools/software, etc.
APU builds kind of negate a lot of that. Since your graphics is built in, and you intend to use it, then most of the rest of the motherboard I/O is probably not needed. But you can still pursue better sound chips and networking.