I had to use government apps as part of their immigration process, the apps were only available in the official app stores. If I remember right they had am all for immigration services, though I know for sure they had a digital ID app that was absolutely required.

The major banks in that country also required apps from official app stores, though I don't think I was technically required to have a bank account. I was in the country under a program based on owning my own consulting business. I did have to prove financials to the government as part of that, but maybe there was a way I could have technically done that without a bank account which required a mobile app.