Aren't the kernel modules kmod-video-core and kmod-video-uvc the required linux driver files?
I found a previous thread where the driver had to be "backported":
Trying to install mjpegstreamer on Flint - Routers - GL.iNet
Despite what the USB port does or does not support, all of my other OpenWRT devices have USB ports that did not officially support webcams, but will work with the Video4Linux driver.
In my case, all of the driver modules appear to install without issue on Flint 3, but the /dev/video0 device doesn't appear when I plug in the camera (it DOES appear on all my other OpenWrt routers).