@Panta, there are about 4,700 banks in the eurozone countries. In the (still) 28 EU member states plus the EFTA countries (European Free Trade Association) there are about 6,600 banks. And how many banks worldwide - no idea.
To feed the e-App Store with this data would be an enormous amount of work. A functional check if every single banking app works under microG - hardly realistically possible.
The banking app manufacturers make it very easy for themselves by using the Apple App Store and G°°gle Play Store for distribution. This leaves the user only the possibility to get the banking app .apk from elsewhere and hope that it works under /e/ OS with microG.
By the way: My two banking apps work very well - including reading QR code.