Unless I've misunderstood what you're suggesting, I think you would need a (20? 40? Gbps) Thunderbolt 3 switch for this to work, because the dock only has one h

Unless I've misunderstood what you're suggesting, I think you would need a (20? 40? Gbps) Thunderbolt 3 switch for this to work, because the dock only has one host port (the dock's topology looks more like a USB hub than a network switch). I suppose there are chips that can do this, but I've never seen a standalone Thunderbolt switch as a product, and if one existed it would probably be expensive. In any case, my desktop is old and doesn't speak Thunderbolt. I'm not sure whether I can bolt it on with a PCIe card, but even if I could, configuring an nvidia card to reroute output from its own ports to a Thunderbolt add-on card sounds... not fun. And then you'd have to deal with the fact that the longest passive cable that the TB3 spec allows for is like, 2 feet long, and I have a standing desk... It's certainly an interesting idea, and pulling it off would be an impressive technical feat.