PlatformIO - Next-generation IDE for IoT
Android - Android is an open source mobile operating system initially released by Google in 2008 and has since become of the most widely used operating systems on any platform.
B4R - Development tool for native Arduino programs.
e.foundation /e/ - /e/ is a fork of LineageOS that aims to be completely free of everything Google.
openHAB - "empowering the smart home" - vendor and technology agnostic open source home automation
LuneOS - LuneOS is a free and open source mobile operating system that respects users’ privacy.