@AppLee I've had another go with the usbotg-dongled mouse.
On my device, it's not doing everything I'd like, or I'm missing the way... Or is it my mouse?

I can see open applications, by swiping from right side, but cannot position the pointer to swipe any up & away. The mouse doesn't open the application drawer with a swipe from the left [aha! just solved this one - push left edge and wait] In Morph browser, how can open tabs be closed by mouse? Scrolling is very slow.
Cheers,
KJU