Is called cash :) It's accepted everywhere.
>official store membership and coupon apps
Should all be burned anyway. Plastic cards and bits of paper worked fine for decades, you don't suddenly need to run arbitrary code on my pocket supercomputer.
>banking apps
Safer to use the website. My bank authenticates you by having you enter your PIN into a card reader - although they have created a mobile app, the security is strictly inferior as phones do not come with card readers (and the passcode is different from your PIN, making you more likely to write it down).
The basic pattern is, it's either important enough to be worth being a stickler over, or trivial enough to ditch entirely. Personally, I find "not being on F-Droid" as a very strong signal that I should not want to use an app in the first place. It steers me away from malicious code and proprietary lockin. And I never, ever see an ad on my phone!