WiFi 6 for the Pinebook Pro

[manawyrm]

I'm a hardware dummy-- so apologies if this is basic: what makes the add-on board specific to the wireless card? Would it support any card with the same M.2 connection?

There's 2 major types of M.2 slots: 
Key A/E slots - WiFi, bluetooth and LTE cards
Key B/M slots - SSDs (either NVMe or SATA)

These are physically incompatible, as they have a notch/key at a different location. 
But with a bit of trickery, you can use a part of the SSD connector to hook up a Key E slot and use a WiFi card.
You could connect any Key A/E card to this adapter.