Here is a US listing for gaffer tape:
https://www.amazon.com/Premium-Gaffe...fer+tape&psc=1
The stuff I found sticks very well, is cloth tape that can be torn by hand. The adhesive is very strong, but can easily be removed.
Once I have a skin or cover for the Oasis I’ll remove the tape, but for now it helps me keep a good grip. I’ve lost some strength in my hands, and many devices are on the slick side. Having to grip too hard to hold on to things also triggers pain in my fingers, so some added texture or grip is a good thing.
The tape is inelegant for sure. But it’s better than dropping the Oasis and I can’t see it when I’m reading.