rangerz
2
If you install a USB wifi adapter you will most likely need to install drivers for the device, assuming they exist. You will also need to at least initially configure the second device in Luci. I am not sure if the GUI will display the second radio correctly.
Unfortunately there is no list maintained of supported wifi adapters for OpenWrt. It’s easier to get 2.4G support, many of the devices have not been reverse engineered for 5G as yet. I think the kmod-ath9k and kmod-ath10k are the most viable options, but the ath10K is not available in the current build of OpenWrt or GLi, only trunk (OpenWrt development). I am still struggling to find a current 5G device.
Some tested dongles are listed here: Overview - GL.iNet Docs (scroll down)
What problems are you having with WISP and what firmware are you on?