Flutter has been transitioning from a cross-platform mobile development SDK for Android/iOS into a tool that allows you to run the same code natively in a browser on Windows, Linux and macOS. With Flutter 2, non-mobile Flutter development is starting to become more viable.
Last year, I wrote two articles here on Smashing Magazine about using Flutter on web and desktop platforms. The first article was a general introduction to web and desktop development, and focused on building responsive UI; the second article was about the challenges you might face when trying to develop a Flutter app that runs on multiple platforms.