Plotly for Flutter web
Flutter libraries for drawing charts are relatively immature as of mid 2021. If you are only targeting the web, a great solution is to use the feature full Plotly javascript library.
See the example folder for usage.
In your own project, inside your web/ folder create a js/ folder
and copy theplotly-latest.min.jsfile inside.
Edit your index.html file and add
<script defer src="main.dart.js" type="application/javascript"></script>
<script src="js/plotly-latest.min.js"></script>
to your <head> element.