CameraConstraint on a polyline

[MauroGentile]

have a FlutterMap with a Mapbox tile layer. The initialCameraFit is set to a polyline with padding so that the view is fit on the polyline with a predefined Padding. The zoom level is obviously automatically determined by the fit operation. From here, I want to limit the pan and zoom so that: 1) the user cannot zoom out more than the initial zoom level (but can zoom in as he likes and go back), and 2) the pan must always include at least one point of the polyline. How do I achieve this? CameraCOnstraint does not seem to be a possible option.