The state of AM5 motherboard is a bit disappointing. The only brand that seems to have 8x8x with an extra 4x card on the chipset now doesn't support ECC...

I may have to start looking into boards without 8x8x splitting on the first two PCIe ports, and instead buy one of those 8-nvme 16x cards with an active hub. Especially since I'm already on a PCIe x4 10gbe card, so I don't have to worry about the integrated network being any good.