i replaced the NVMe drive that was on the glitching PCI node, and the errors subsided for now. i also ordered amazon.com/gp/product/B09XSY3JVS which will hopefully allow me to move off it completely. AsRockRack support has not been able to help.
What, specifically, are your needs that you are referring to?
If you know your only "high end" need is a ton of M.2 slots, you don't specifically have to limit yourself to just high end boards. You can always get a PCIe to M.2 expansion card: https://www.amazon.com/ASUS-M-2-X16-V2-Threadripper/dp/B07NQBQB6Z
With those, any LGA1700 board with at least 2 full x16 slots is viable.
If you have any pcie slots left there are adapters for more m.2 slots. Asus makes one, as does Konyead. Note that these are x16 and therefore will split a x16 slot into 4 separate x4 m.2 slots, they will not split a x8 lane into 4 x2s or a x4 to 4x1s. So if you use a x8 slot only the first two m.2 slots will work. Also, your motherboard must support pcie bifurcation, a lot do, but some don't.