Jonsbo N3 case - 8 hard drives
If you're OK with a meager CPU and ordering from Aliexpress, you can grab this mini ITX board with a Celeron N5105, has six SATA ports, and two M.2 NVMe ports, 4x 2.5Gbps Intel NIC (amazing actually), support for 2x DDR4 So-DIMM (laptop) RAM: https://www.aliexpress.us/item/3256805947799076.html
Or just search NAS motherboard N5105, there's plenty of sellers.
Specs say 16GB max RAM (mainly Intel CPU published limit) but it apparently works fine with 32GB.
You can use one of the M.2 slots to add an M.2 to SATA port adapter: https://www.amazon.com/dp/B07T3RMFFT
Or buy the M.2 SATA adapter from Aliexpress if you get the mobo, they're cheaper and basically the same thing.
And because it includes dual M.2 slots, four 2.5Gbps ethernet ports, and 6 onboard SATA it leaves the PCIe slot free for further expansion if desired. I don't know why more mainstream motherboard manufacturers don't do this, but with a socketed CPU.
I'm doing a review of this kind of setup once my motherboard arrives.