Kivy and kivymd are installed with pip. See the install directions for each package.
You can add documentation to Cursor in the chat box, typically on the right hand side, entering @, selecting docs, and entering the root web site for the docs. You could add the code by a similar process and pointing to the kivy code in the .venv. When I
was first getting started with cursor I found a few videos and blog posts that provided more up to date info on cursor that the cursor documentation. I don't know if this is still the case. They team at cursor continues to add features rather quickly.
It is also worth adding that cursor provides a number of different underlying AI engines. If you feel you are not getting good results, try a different AI.
I have not seen a concern about kivymd stability. The newest version of KivyMD has some improvements for performance, and is more up to date with the Google Material Design Spec, last time I checked it must be installed from github. The 1.x version has some
features (DataTables for example) that are not in version 2.x. I think this may be because DataTables are not part of the newest MD spec - but I could be mistaken.
Note: There is a change in the KivyMD API where 1.x and 2.x are not compatible. My suggestion is to use the 2.x version.