You don't think that is comparing apples and pears?
This is an Ultimaker printer, using Ultimakers slicer, what does octoprint has to do with it?
I know it would require printer firmware updates to do this.
Perhaps you've never used an Ultimaker S5? The printer allso knows the material, Just as Cura knows, it is selected from a list within the printer when the material is loaded, so the density parameter should not be that hard to include.
I know it would require printer firmware updates to do this. Hence why I'm asking about it, requesting it so perhaps some clever engineers at Ultimaker can see it and give it a thought.