I don't know of any, sorry.Maybe (definitely) off topic, but I figured you would be more familiar with the nebulous world of Gen 4 PCIe adapters.
Have you seen any sign of Gen 4 M.2 to PCIe adapters? With TB4 being a pathetic retread of TB3, but miniPCs and mini ITX boards supporting PCIe 4.0 M.2, it could solve the GPU PCIe 3.0 x4 bottleneck.
Giving custom setups and certain sandwich cases the opportunity to add additional devices.