I always received beacons with Country "US", until I created the file "brcmfmac43456-sdio.xunlong,orangepi-4.txt".
It is a copy of brcmfmac43456-sdio.txt and I added the line:
With this modification, I see the expected beacon. (Country: "DE", correct tx-power, ...)
I think this is not the intended way to configure it.
What I checked before:
My hostapd.conf contains;
iw reg get
country DE: DFS-ETSI
(2400 - 2483 @ 40), (N/A, 20), (N/A)
(5150 - 5250 @ 80), (N/A, 20), (N/A), NO-O