MCAS - Prevent upload of unlabeled files in Teams Desktop app

I'm trying to implement this

The only way I found to make it work in a Session Policy is to use the negation and select all existing labels

If I leave the file filter equals empty (don't select anything) then the filter is not applied

Is there a way to apply this also in desktop apps like Teams, Word etc.?

Session policies are only applied to web sessions

Access policies will prevent/block access altogether