The reason the SSV6051P driver works on the RK BSP kernel (and current Amlogic BSP kernels) has nothing to do with RK having better open-source compatibility. It is simply due to RK using an old kernel. I forget the exact kernel version where things break, but once you move beyond Linux 4.11 or 4.12 there are major crypto API changes and the driver no longer compiles. If you're lucky RK might task one of their internal devs to rewrite it at some point, but IMHO that's a long shot.
The last time I checked for an LE S905/x/w image for a generic box with SSV6051P wifi chipset, c. Sep 2019, the AP mode didn't work.
So is there an LE S905/x/w image version on which the AP mode does work?
I know this is more an LE question, but then it helps to compare with RK image too which works with AP mode.