At the end of the day, you’d run the same Linux stack you would on a non-x86 accesspoint, driver that loads the firmware + combination of iw and hostapd for control. I don’t know of anyone successfully using FreeBSD drivers (on modern cards).
Cards (worth using) would usually come in m.2 form factor and you’d typically end up using a slot adapter, because of thickness and cooling and noise/interference and you’d get the biggest gain u.fl antennas you could find.
Compex.com.sg sells ath11k 802.11ax modules that work with 5GHz for about 200, once you add shipping, adapter, antennas from your favorite Chinese hardware warehouse, it goes to about 250 if you’re careful, 300 if you buy from Amazon and are less careful about cost, … and then you need 2.4GHz (cheap but needs a separate adapter) and another 350 if you want 6GHz (different adapter+antennas).
It’s definitely doable, people who hack on drivers and wifi software have setups like these as their daily driver wifi at home.
I’m not sure it gets you any more flexibility compared to running OpenWRT which is the same stack (Linux kernel+hostapd+iw) on a quad core arm router/accesspoint - and those tend to be quite a bit cheaper
The Intel card you mentioned, the firmware for it wasn’t built with AP mode in mind, they usually have some AP support because end users want to be able to e.g. transfer data from one laptop to another. Because staffing an organization that can develop and test firmware and drivers costs $10-$50 MM/year. (30-150 people, depending on what size company and what common corporate infra they can rely on). So, they develop / maintain / test / ship / support as few firmwares if possible.
So, you end with ax200/ax201/ac210 that can send beacons going “hi I’m an AP” but you can’t try using certain crypto features and as soon as tickle them card either crashes, or returns an error that confuses the driver and software.
Apparently you can run ax200 in AP mode using wpa_supplicant instead of hostapd (even though they’re built from the same tree/ e.g. on OpenWRT to save space they’re the same multicall binary), because of different startup process that doesn’t mess with the features that are disabled in the wifi chipset firmware.