Actually found the exact product I needed for pcie-splittery on this (albeit older, but codes check out) post: PCIe Bifurcation Splitters?
Pretty sure I saw some pcie gen 4 stuff on the ameri rack website.
Edit: I emailed them when I didn’t see what I needed and they responded quickly, basically doing a non-advertised (no way its custom for what they charged me) item so worth an email to them. That said, I’m more than happy to.pay someone $75 be done with searching and get exactly what I want.