H6 boxes all have no mainline DTS
One is coming in 5.2 I believe, Beelink GS1.
is there a way to recognise which WLAN module is connected to an SDIO bus? I couldn't seem to find any way of doing this...
Yes, each SDIO device has it's own ID, just something like USB, so autoprobing should work. That's the trick I used with old OpenELEC images. Just apply power and proper driver should be loaded automatically (if exist). Fortunately, it's same power pin for both variants. However, brcm based wifi probably still doesn't work due to missing config file and firmware. I'll fix this next week.