Asus and Acer motherboards supports bifurcation on pcie slots. So for example you can enable this in BIOS and put Asus hyper extension card to put 4 nvme disk into pcie slot https://www.asus.com/support/faq/1037507/

There are other cards like that i.e. https://global.icydock.com/product_323.html This one have better support for smaller in size disks, much easier to swap disk but costs like 4 times more.

I think it could put even more drives in my new case I.e. using pcie to u2 card and the using 8 drives bays. But this would cost me probably like 3 times more just for the bay with connectors. and I do not need that much space.

https://global.icydock.com/product_363.html

If you like u2 drives then icydock provides solution for them too. Or if you want go cheaper there are other cards with slim-sas or mcio https://www.microsatacables.com/4-port-pcie-3-0-x16-to-u-2-s...

But u2 disks are at least 2 times more costly per GB. Like 40tb costs 10k$. This is too much IMO.