The polar plot function ignores unitized data units in the v0.91-maint branch, I have yet to test it with the main branch.
Currently the xaxis and yaxis manage the unit conversion, but since a PolarAxes does not have and x and y Axis object there is
nothing to do the conversion and it gets skipped, one possibility is to have the PolarAxes manage a pair of converters for the
'theta' and 'r' axes.
I plan to really test out the main branch later this month and will give feedback if this exists in the main branch.