I came here after searching on another thread I will post about. Just sharing some info here re: RTL8812AU.
Literally today I got this:
https://www.amazon.com/gp/product/B07FC ... UTF8&psc=1
"BrosTrend 1200Mbps Linux USB WiFi Adapter .. 2.4GHz, 2 X 5dBi Antennas, USB 3.0"
It's chipset is Realtek RTL8812AU. It works on the pi 4 - actually following the included instructions and ultimately loads a 88x2bu driver:
root@raspberrypiforme:~# lsmod | grep -iE 88x2bu
88x2bu 2342912 0
cfg80211 679936 2 brcmfmac,88x2bu
I get about -53 dbm from about 45 feet away but the pi is behind a closed door most of the time.
That's a step up from the -62 dbm i was getting from the onboard wlan adapter.
I tested w/no case because the aluminum whilst keeping the pi cool really hampered the wifi.
I was using wifi man on my Android.
I am running hostapd and raspap-webgui.