3 M.2 slots is common even on AMD's mainstream X570 and B550 platforms. I don't know if any of those motherboards also bundle riser cards for further M.2 PCIe SSDs, but they do support PCIe bifurcation so you can run your GPU at PCIe 4.0 x8 and use the second x16/x8 slot to run two more SSDs in a passive riser purchased separately.
The b550 Aorus Master I just got is unique in its bifurcation. It maps the CPU's gen 4 PCI-E to the main 16x slot and one M.2 4x, or drops the 16x slot down to 8x and then has three gen 4 M.2 4x. The other two PCI-E slots are gen 3 through the b550 chipset.
I chose this board for its absurdly overkill CPU voltage regulation. The pci-e configuration seems like a pretty good compromise, though.
