Creating TH2F and TH3F using macros in TTree::Draw and TTree::Project?

I just discovered the feature where TTree::Draw uses MakeProxy to read macros, e.g.

I can already think of a few handy uses of this. One thing that doesn’t seem possible, however, is drawing to a multidimensional histogram with this feature. Could it be possible for a macro with a signature

to be used to draw a TH2F? Additionally, could this feature be used with TTree::Project? (which appears to just produce a string and passes it to TTree:Draw).

This is an interesting idea (where one challenge is to properly handle the case where the user had defined both the expression and expression2d function). Would you be interested in helping to implement it?