HN user
Too slow for what? How slow do you think python is? unless your application is cpu-bound (which it probably isn't), python is fast enough for basically anything you might want to do these days, and if it is, you can use cython to optimize the parts that needs to be fast, as kivy does.
Did you check the gallery of apps done with kivy, on android or else? Much can be accomplished, i promise you. https://kivy.org/#gallery
here are a few of the apps i personally developped fully with kivy https://vimeo.com/297757037 https://vimeo.com/257492885 https://vimeo.com/206290310 https://vimeo.com/144659031 https://www.youtube.com/watch?v=Umls6ytXasU https://www.youtube.com/watch?v=2EF5W-d2eVI
python can do so much more than ML, reducing it to that is short sighted.