Hey, good news, problem solved.
I checked the Wyze video folder (where the 12-sec clips from viewed notifications/events are stored locally) and there were 1700+ files in there.
Cleared that folder and I had access to the App Settings menu again (no crash.)
Just FYI, Android > Settings > Apps > Wyze > Storage > Clear Cache
is not the same as
Wyze app > Account > App Settings > Cache File Size > Clear
The former does not clear the Wyze video folder of accumulated clips as does the latter.
And as it happens, the Hardware Decoder setting was OFF - turning it on definitely improves performance on this tablet (especialy when viewing footage from SD, unusable without it.)
-peep