> It seems that Alder Lake no longer support x8/x4/x4 sadly.

Sort of. support is "Up to 1x16+4, 2x8+4" [1] so could be used as x8/x4/x4, the remaining 4 lanes are unused in the x8, as there are 20 PCIe lanes on the CPU.

[1] https://ark.intel.com/content/www/us/en/ark/products/228441/...