Learn how to read through the Krita API
For granular control using Krita, it has its own API for doing various actions. Probably the biggest thing that can be confusing is knowing what uses the Krita API, and what is using another API like PyQt5.
Probably the best way to look around is to check out the documentation for the Krita API.
It is quite a bit smaller than PyQt, so it shouldn't take that long to look around to get a feel for the types of things you can do. It is also easy to forget that many things can be done using actions, so make sure to check the Action Dictionary out if you cannot find something in the Krita API.
Head to the Krita artists where we have a dedicated area for plugin development and give any feedback you might have.