Termux - a terminal emulator application for Android OS extendible by variety of packages.

Telegram for Android source

The Clojure programming language

OsmAnd

an open source geocoder for openstreetmap data

AnLinux allow you to run Linux on Android without root access.

PC-style productivity for Android

converter that creates three-dimensional models of the world from OpenStreetMap data

configurable OSM offline router with elevation awareness, Java + Android

Matrix <--> E-mail Bridge

Android 10 Desktop Mode example using Lawnchair and libtaskbar