Taming UDF State-based Architectures. Real Cases in Large Applications

UDF architectures that give outwardly a single state (TEA, MVI, Flux, Redux, MVU) are increasingly making their way into Android development, and a lot of people are interested in them. But how to use such architectures in a large, running project? How do you migrate to them and solve common problems elegantly and simply? 
I'll talk about this through the lens of the TEA architecture.