> I don't want to be forced to have my spinning platters connected via NVMe and a series of connector adapters.

I want to build a mini PC-based 3D printed NAS box with a SATA backplate with that exact NVME connector adapter setup!

https://makerworld.com/en/models/1644686-n5-mini-a-3d-printe...

The reality is, as long as you have PCIe you can do pretty much whatever you want, and it's not a big deal.