

Yeah, adding to your post, Threadripper also has lots of PCIe lanes. Here is one that has 4 x16 slots. And, note, I am not endorsing that specific listing. I did very minimal research on that listing, just using it as an example.
Edit: Marauding_gibberish, if you need/want AM5: x670E motherboards have a good number of PCIe lanes and can be bought used now (x870E are newest gen AM5 with lots of lanes as well, but both pale compared to what you can get with Epyc or Threadripper).
All I did for that one was search “Threadripper” and look at the pictures for ones with 4x x16 slots that were not hella expensive. There are technically filters for that, but, I don’t trust people to list their things correctly.
For which chipsets, ect to look for, check out this page. If you click on Learn More next to AM5 for example, it tells you how many PCIe lanes are on each chipset type which can give you some initial search criteria to look for. (That is what made me point out x670E as it has the most lanes, but is not newest gen, so you can find used versions.)