> Banking or CC app for mandatory 2FA?

Switched banks.

> gvmt Covid mandatory app to travel anywhere?

There wasn't one, thank $DEITY (Germany).

> QR code for restaurants?

Never encountered one without a menu yet, but I'd just go to another one.

> Places that require an app in general?

Never encountered those, either. There was one on my offline backpacking trip which required digital payment. It was sad, but I had to forfeit.