Does OPAL support use of a USB hub on the integrated USB port? Can applications (plug-ins) running on OPAL, access devices on the USB port?
It can but it comes down to the quality of the chipset inside said hub. Not all communicate properly to a Linux kernel & the price/port ratio is usually a good indication of this. You’d also want something w/ a power block as trying to share a sole port’s 900mA (per the USB 3.0 spec, 500mA USB2.0) across multiple attached devices is just going to set yourself up for a bad time.
Personally I don’t bother with hubs at all these days but if I were to, I’d look to what’s being used by those running RPis &/or Anker, UGREEN’s offerings… but be sure to test thoroughly before the return window closes.
logread -e usb should be handy with that.
That’s a whole different potential ‘kettle of fish’ you’re looking at there. In short, yes, but nearly the entire firmware, almost everything, has to be moved over to the USB drive to do so. It an be done but it’s a matter of ‘only if you really, really need to.’
A bad power spike could really ruin your day using such a config; specifically potential filesystem corruption from an unclean dismount of the drive/storage. It is a way of taking a small/nearly filled storage on a device to a much larger one, though (eg: Certa, GL-AR750, default 16MB onboard to 974MB on uSD) however… but it’s not my first recommendation to do so.
Related thread re: external storage expansion to run onboard applications
Related thread re: power