Last time I tried, what I found was missing is some guidelines on how to architecture an application. For the web, we have React, Angular and plenty of frameworks to choose from, which help having some base app skeleton to build on top of.

In Qt (QML), I couldn't quite find something like this and I had the feeling I needed to create my own framework from scratch, which is hard when, at the same time, you need to learn a new technology. There were some random ideas in various blogs and articles but nothing major or at least no officially supported one.