Doing that for decades.

An app for Windows phone, downloaded 140k times: https://github.com/Const-me/SkyFM

Cross-platform graphics library for .NET: https://github.com/Const-me/Vrmac

Recently, offline speech-to-text for Windows: https://github.com/Const-me/Whisper

At this point, I consider side projects like that as a hobby.