This repository contains an example python-for-android application using the android.presplash_lottie option of buildozer, allowing to display short animation instead of a static image while the application starts.
Lottie is a vector format (hence quite lightweight) documented at http://airbnb.io/lottie/#/. You can find a lot of neat examples animation of this format at https://lottiefiles.com/
You can design your own (or edit existing ones, provided the author granted such permission), using various tools. Aside the popular (but expensive) Adobe After Effect, you can also use Synfig (free/open source) which can also export animations as lottie files as of 1.4.0.
This project is built using github-actions, so provided a recent enough build happened, you should be able to download the example apk package from the "artifacts" section of a recent build.