All the computers at my home are laptops, and a thunderbolt 25Gbe do exist, but they are huge and cost $900 lol
there’s the H13SSL-NT, but uses broadcom
I hear everyone say that Broadcom-based networking is very unreliable. I see everyone recommend Intel-based NICs for 10+ Gbe.
If the only difference of the cheaper H13SSL-N
the lack of Broadcom 10Gbe, then getting it and pairing with a PCIe SFP card seems like a good choice to me.
pretty rare to need more now adays
HBA + Hyper M.2 card (for Optane SSDs) + NIC is already 3 slots.
And then you may want a GPU (or even 2 - one for compressing camera streams and one for transcoding Plex/Jellyfin) , a second HBA eventually, etc., etc.
I am willing to invest into a proper enterprise CPU + MoBo for the PCIe lanes. If the slots are limited, then this defeats the purpose for me personally. That’s how I look at it. But you are totally correct: most people don’t need more than that nowadays! 
There are equivalents available from other manufacturers, but we used models identical to the approved ones from the QVL available direct from SK Hynix but substantially cheaper. Don’t have the part number handy and haven’t built a Turin yet, only a bunch of Genoa generations.
Did you have any issues? Would you be able to look up the part number by any chance? I am scared of getting incompatible sticks and having to deal with the pain of return process. I read horror stories where people spent tons of $$$ on RAM that was supposed to match (speed, latency, etc.) and yet it didn’t work. MoBos nowadays are too finicky!
Also… Do you remember how much you paid? The DDR5 RDIMMs costs that I looked at are insane.
THANKS!