How the Sigma C 45 mm f/2.8 DG DN fits that scenario? Not in a perfect way, to be sure. It is a bit too big, too expensive, and its optical performance is not outstanding. In objective terms it is a well-put-together lens, with just one serious flaw, high vignetting, and a lot of serious assets.
very solid, sealed casing,, excellent image quality in frame centre,, good image quality on the edge of the APS-C sensor,, acceptable image quality on the edge of full frame,, very low lateral chromatic aberration,, slight longitudinal chromatic aberration,, sensible coma correction,, moderate...
not especially accurate autofocus,, high vignetting on full frame which, additionally, decreases slowly on stopping down.