I’d rather have the whole thing in a single case of the same size. Unless you want to be able to unplug the mini PC for standalone use, or you happen to already own the mini PC and want to upgrade to a dGPU without migrating to a new PC, I’m not sure what the benefit of this setup is.
It's a proprietary edge connector that connects the dock and the mini PC, but it carries standard PCIe, so it's at least twice as fast as Thunderbolt.
To me all of these Mini PCs are essentially uselessly uninteresting without fast network connectivity. When is an actual vendor that is not Quotom or whatever ship one with 10GBaseT or SFP+/SFP28 ports already?
Idk, with the money you use for a docking station, graphics card and the mini PC itself I feel like a regular desktop or mini atx build is more suitable.