For detailed logs and the code please check my colab notebooks below:
most basic attempt: https://colab.research.google.com/drive/1FhDPxcxOy562cl9hlLnTTotxnpKbe7Wk?usp=sharing
p4a manually: https://colab.research.google.com/drive/1zB1xK1lCNjpd7Z3JZz2vrh0yul7HZ0wY?usp=sharing
desparate final attempt: https://colab.research.google.com/drive/1hyef6UwhZTb7EZDqmIofe1r9Wub2wIBq?usp=sharing
I would highly appreciate your help, I'm kind of at a loss. No other current question was answered and the kivy subreddit seems to be dealing with the same issues and giving up because there are no propper answers anywhere. I hope this post can become the main point to start the debugging.