Hi, would it be possible to publish schematic for Penta Hat m.2 key -> IPEX?
I would like to modify it a little bit to better fit my purpose. Currently IPEX connector is position 90deg to the m.2 key, I would like to put it 180deg and on longer board
What board You are using? Maybe You just have wrong adapter? Can You please post photo of it?
I think this one is designed for ROCK 3C
Certainly You did not wanted such cable/adapter spaghetti to connect with smallest RK3588 board available 
Opi max 5 is the only board that packed full size 2280 m.2 slot under pi format SBC. There were few boards with m.2, none other pointed in that direction. They also did not included 2230/2242 mount point.
Of course You can quite easily write pinout for this adapter, this is super easy with multimeter. There is no power section, no active components, just easy to see and measure pins. Perfect board would look like the one for ROCK 3A/4, but rotated 180deg:
Notice mount points on sides. They are used to place board and use holes from radxa boards. Opi needs own placement for those. Easy when You design Your board. Just make sure everything else works with curent setup and You are sure to go though this path. This HAT makes sense when used with factory case when everything fits perfectly, otherwise it will enlarge everything, so it makes same sense just to use one of m.2 sata cards.
BTW, there are some 180 deg m.2 adapters like this one:
with such adapter (there are of course in 2280 size) You could try ROCK 3/4 adapter (probably screw mounts will not fit, but may be possible to drill right one, no signals there).
Also You can try to mount card You already have and just get longer IPEX and bend it as needed. it should survive that easily.
It does not work. Opi5Max dont recognize the board. I tried Opi official images, armbian, DietPi, freebsd and nothing recognize the board. When I run lspci it does not show up as Sata controller 
Btw found it for anyone else interested https://dl.radxa.com/penta/hw/
Actually that is only for hat and not the adapter. Better then nothing though
