So. I was trying to create a simple quick assistant manager plugin. I wasn't really a programmer, and I'm completely new to Python or even Qt. It was a simple plugin so i thought it wouldn't be so hard.

I was wrong.

What I want to achieve is a simple shortcut to activate/deactivate assistant depending on which key pressed. Example, press '1': assistant number '1' activated, press '2': assistant number '2' activated.

But, from what I understand,
Krita is written in C++,
Python Plugins can only calls certain functions that Krita has provided,
assistant tools doesn't have 'python plugin integration'.

Is there any way to create this plugin in python, or should I learn to create a C++ extension instead?

No, I'm sorry, at this point that's not possible from Python.