I maintain and develop a FOSS repository on GitHub and I intend to migrate from Electron to Flutter.
What is the proper procedure for this?
I want to keep the name and community but it also feels a bit messy.
Do I just wipe everything old on the main branch and keep a branch that reflects the newest Electron version or do I move to a new repository and start over?
Tips and feedback is appreciated!

If you care about stars on GH then maybe a new branch is in order. But to keep history I'd say creating a new repo and archiving the old one is the way to go.

I think releases disappear if their matching tags do (which would happen with a clean slate) and that would be important if you attached binaries (although could still be built from source). Existing stargazers would more easily miss that the repo lives on elsewhere.

Branch option is simpler IMO. Also bit easier to check for feature parity during the initial migration going back-and-forth from 1 to another

@webketje I agree, branching would be simpler in this case.

Also, first Flutter and by extension Dart developer I see in this platform. Would like to hear more about OP's experience in developing with Dart and Flutter.

@AleCx04 Flutter is both smooth and frustrating at times. It's easy to pickup coming from JS and the developer experience is one of the best imo.
The biggest let down are packages/libraries which often lack up-to-date documentation and proper support for different platforms.
The most important thing for me is that I'm having fun when building stuff with Flutter :)