Is it possible to do a SBC (Raspberry Pi w/ M2 HAT or RockPi or ...) with an AX210 M2 NGFF to get Wifi6E running as an AP?
No, the AX210 does not support AP mode at 5- and 6 GHz (only in a very limited fashion on 2.4 GHz, using channels 1-11).
@cchance27 you can wait for this device :
They have a topic on their forum : https://forum.banana-pi.org/t/banana-pi-bpi-r3-router-board-with-mediatek-mt7986-filogic-830-support-wi-fi-6-6e-2-5gbe-sfp/12933/2
problem isn't really the board, there are plenty of those, with a M2 slot, but the radio ...
Is this a HW or a FW/driver issue?
Probably both, the firmware does not allow initiating radiation above 2.4 GHz
<fullstop>, the hardware likely doesn't provide the means necessary to deal with DFS properly - or Intel didn't want to go through certification, doesn't change the results though - it's not going to work (and given Intel's track record with AP mode, never, they very intentionally make this impossible).
Apart from this, iwlwifi/ ax210 doesn't exactly perform great on 6 GHz in STA mode either (while their windows driver does work) - and that's an understatement.
Unfortunately intel cards are often the most available ones here.
Also in clients regardless if windows or linux it's long no more my favourite especially when trying to use ch. 13...
A rotten banana is also easier to get than a decent AP capable wlan card - and it will be just as good as an Intel card for this task.
I would fit my laptop with a rotten banana today, if it had a slot for it and no blacklist in the efi
A notebook usually doesn't need AP mode, which is the important difference here.
True but never the less also in client mode they seem to be crapier than others