I'm going to apu2 but i can not find any relevant info which wifi cards are supported / used except of wle200nx / wle600nx, this card is not available in our country, but also elsewhere.
Which modules you use to get the least trouble running under linux. It may can to use an some older card with from laptop or buy from bazar some card, etc...
The stores offer the most microtik cards for routerboard, I do not know how they work with apu2 or overall with pc engines.
What are the most common other wifi cards you use?