I made a sub-100k Android app once (I am now banned from the Play Store, and I should be lucky they didn't delete my Gmail account too) and every time I opened the IDE (Android Studio at the time) it would automatically add a Google "support library" to the project that Google obviously wanted to force me to use. If I forgot to remove it and built the app, it would be closer to 10MB. So that was the minimum size of almost every Android app at the time.

Most Android apps are huge because they bundle tons of assets just to accommodate the “initial experience of the user”. Also, using bloat libraries and frameworks (any shipped by Google), increase the apk size.

Nowadays Google offers a solution for this problem called app bundling. It’s especially good if you build a mono app that behaves differently in certain regions. Instead of delivering a raw apk, you deliver a region specific app bundle.