Intel cards in particular will flat out refuse to work in AP mode on the 5GHz band due to a poorly implemented regulatory domain check.

On the other hand, my generic AliExpress Mediatek MT7612U works in AP mode. If I recall, it was passable, but it didn't perform that well compared to my dedicated AP; I think it was the range that wasn't as good (probably had something to do with my antennas). I also didn't test it with a lot of clients.