The requirements say that you have to be on the beta branch:
flutter channel beta flutter upgrade flutter config --enable-web
Then you add support for it like so:
flutter create .
Finally I tried running it by pressing Option+F5 in Visual Studio Code. It then asked me to allow `http://[::1]:63105/`. Even though I said yes, the Chrome tab crashed, failing to load the service worker. At the same time, VSC showed me this spinner:
I found the same issue reported here: https://github.com/flutter/flutter/issues/40257
It seems that running it from the command-line as explained in the docs works, so I'll stick to that for now:
flutter run -d chrome