@bjlockie to use the MediaTek MT7612U kmod-mt76x2u need to be installed after that it will show up on Luci and can be configured as AP or STA.
The built in Broadcom on the Pi 4, it should work with this setting :Raspberry pi 4 access point
Realtek 8812au seems to be broken on the latest snapshots ,it used to work before, like in this old snapshot :https://drive.google.com/file/d/1HXlbTqis-QoOi8QrJBUg0ZAvtovOz26B/view?usp=sharing