Get references to glyphs in plugin

I use MuseScore 3.6.2 and can get bounding boxes of objects like Note, Chord, Accidental and so on. But in the case of Key-Signatures for example, I need the bounding boxes of the individual sharps/flats/naturals and for rests bigger than eights of the individually stacked eighth rests. Is there a way to get these more findamental glyphs exposed to the Plugin API?
I use this for automatic dataset creation from musicxmls. It would also be great if the exact shape of the glyphs could be recovered to make instance segmentation maps.

Is something like this possible as of now?