Our product Feather is based on this one. If you want to try running a few Flutter apps on macOS, see the 'Sample Apps' section on this page: https://feather-apps.com/
Making it feel like a desktop app might be something we tackle in the longer term. But my personal view is that platform fidelity isn't particularly important as long as an app is fast, responsive and looks good. eg. Gmail and Spotify have been wildly successful without needing to look like native apps.