How to draw a real-time line graph with a stream of values?

Not sure if this will help but I have just added a plugin to Flutter that may do what you need, or if not at least give you some ideas. You can find it here

And in this gist I have modified the example code to read the data from the device sensor stream (in real-time) which it then graphs out.

I recommand mp_chart which is basically the dart version of (the great) MPAndroidChart.