Information in this topic is very outdated see this topic.
On 150balbes 4.18.0-rc5 Ubuntu images, for those with T95 (p200) AML tvbox using meson-gxbb-p201.dtb / 200 device tree file, there is a problem with wifi caused by an error with nvram firmware files.
Problems manifests as wlan0 present but can't see any AP's.
To fix, use
mv /lib/firmware/brcm/brcmfmac4330-sdio.txt /lib/firmware/brcm/brcmfmac4330-sdio.txt.old
ln -s /lib/firmware/brcm/nvram_ap6330.txt /lib/firmware/brcm/brcmfmac4330-sdio.txt
in a shell on the target