There's a similar adapter with one positive review on Amazon: https://www.amazon.com/Bplus-Adapter-Socket-PCeI-base-dimension/product-reviews/B00T8ULDPY
Out of curiosity, are you trying to run 8 GPUs on your motherboard?
Yes the goal is for 8 gpu's but I only have 4 currently. I made sure that i had no sata drives in 5/6 ports on this motherboard as they share the M.2 port. It still did not recognize. I will say I watched 2 videos, 1 of a person installing a M.2 SSD that worked fine and another of a user who had the asus z97 and the bios actually had M.2 options to set. I dont think it would be a huge custom bios to just get 8 gpu's on this board, maybe with 10+ but it should not be so complex that I cant get 8 working. Yes I could buy another cheap MB/CPU but I dont want to, If I go that route I might as well do what everyone else does and just build 6 gpu rigs.