How to stick xteink x4 to android phone / case without magsafe? Can someone recommend a strong magsafe sticker or what are my choices?

I have a case for my pixel 8 pro that I like but it has no magsafe ring. How can i stick the X4 to the back of the case? Are those generic amgsafe sticker you can buy (from amazon germany) good enough? When ordering the X4 should I also order the Magnetic Stick-On Ring?

Can someone could recommend a way how to handle this magnetic sticky thing and how to upgrade any non-magsafe case ?