I forgot about Airetos completely, will check with them whats the lead time
Even that FN-Link is now in most of the places (including Alibaba) out of stock (maybe single pieces here and there, some are still available on Taobao).
Yes, QCA639x is a budget option, but that FN-Link is a really bad one with 11 dBm only.
I have seen others that claim 16 dBm or more.
It's not the M.2 that's the issue on QCN907x but rather the fact that they require 5V which is not present on M.2 or Mini PCI-E at all, so you cant just plug it in.