An external GPU would likely use a PCIe x4 slot instead, with only four lanes. That doesn’t make it four times slower, but it does have a non-trivial impact on performance.

A PCIe USB expansion card is a cheap and quick solution, making use of that vacant PCIe x1 slot. Instead of getting a USB hub ...

1 x M.2280/22110 PCIe Gen 4×1 slot 1 x M.2 2230/2280 PCIe Gen 4×1 slot You can also use M.2 to U.2 adapters with the M.2 22110 slots if you’d like to use two U.2 drives.

Performance over OCuLink would be less than the PCIe slot on the Beelink GTi12 Ultra, and this system is more expensive. Check out our GMKtec NucBox M7 Pro review ...

OWC Express 4M2 offers fast external storage at a modest base price, but peak speeds and reliability depend on RAID, software, and user configuration.

Up to 192GB of DDR5-7200+ memory is supported, as is enthusiast-grade 2.5GbE ethernet, 2 x SATA3 ports, 1 x Blazing M.2 slot for a Gen5 SSD, ... enables PCIe Gen4 x4 for external GPUs; ...

Best external hard drives: expand your horizons ... Z790 might if manufacturers opt to configure a board with a 8x PCIe slot and two 4x M.2 slots but that's a story for another day.