I've currently been using an Asus USB-AC51 (MT7610U) as my uplink on a Brume 2 running firmware 4.6.4 for several days with no problems.
I haven't tried AP mode, nor will I at this point.
I just wanted to note this, because I've waited about 4 years to be able to plug a mt76 dongle into OpenWRT and/or GL.iNet's firmware and have it work without problems, and that's finally happened. The bugfixes are arriving!
It works for uplink but the GL.iNet firmware remains in "No internet connection! Find a network to reconnect" mode because it doesn't expect uplink from wifi... so, some GLi functions don't work.
Since I last posted, I'm in another city and back to using wired uplink, and also flashed vanilla OpenWRT on the Brume 2, so I can't get a screenshot at the moment
I guess my description of the issue I saw is that, when a non-wifi router such as Brume 2, which is running GLi firmware, successfully gets uplink via a non-supported wifi dongle, the GLi firmware doesn't properly understand that it has uplink. Some features work and some don't.