mk24: Thanks.
Yes. Once I got eth0 to static 192.168.8.202
(outside my home router's DHCP address range).
I was able to use 'opkg' to install 'LuCI' and
the driver for my TPLink UE300 gigabit USB 3.0 to ethernet adapter.
([SOLVED] Raspberry Pi 4 and TP-Link UE300 USB Ethernet dongle)
I think I used
uci set wireless.radio0.htmode='HT20'
to switch from 'VHT80' to 'HT20' so that my cellphone would see the 'AP' on wlan0.
Chuck