I have a NVME M.2 SSD (250 GB) to attach to the board. Also currently installed is a Gigabyte GT 1030 gpu, having disabled the vega graphics.
off the top of my head i think you can get 8 lanes but the AMD page on the CPU does not say anything
https://www.amd.com/en/products/apu/amd-athlon-240ge
This is what Wiki mentions about the maximum PCIe lanes the processor supports: Athlon 240GE - AMD - WikiChip
I imagine the 1x8 means PCIe lanes and 1x4 means lanes for M.2 or NVME on the motherboard.