So these cables will all work, and there are even existing pinout diagrams for them. We just need manufacturers to start making them in larger quantities. I am also trying to force the issue myself with several oem's and with TE connectivity myself, but many oem's are waiting out the next few months to see what happens. All of these cables should have been already available, but due to the pandemic and everything else (chip shortage, and a return to older tech) the manufacturers aren't in a rush anymore to produce these cables. They are starting to come out, and you can find some things here and there, but for now, it's still tough, or super expensive.
That being said, its not impossible. There are a few sellers who carry them, although the prices are abit high, or you have to wait to get items from China, which could have long wait and lead times this time of the year.
Check here on Alibaba:
SFF8654-8i to Dual SFF8087 Cable
Or if you don't mind the higher price, Areca has them for a marked-up price (horribly so) but they do have them.
Check here:
Areca Cineraid SFF8654-8i to Dual SFF8087 Cable
Scroll down to the third row of cables and it will be there.