I built SwiftUI and Combine features for Joe Wicks' Body Coach while I was at usTwo. It serves tens of thousands of users a month, backed by GraphQL.
The part worth mentioning isn't the stack. I instrumented usage metrics and we used them to decide what the team built next, which sounds obvious and mostly isn't what happens. Teams usually build what was on the roadmap in January. Having numbers means an argument about what to do next can be settled rather than won.