Works with a plain adapter
Sigma SA sits 26.00mm further from the sensor than Canon EF-M. You need a 26.00mm adapter, but it can be a plain one — a hollow metal spacer with no glass in it. The lens still reaches infinity focus and nothing is added to the optical path.
Coverage & framing. The lens covers more than the sensor needs, so the body crops into the frame — roughly 1.6×. A 50mm frames like a 80mm would on Full frame.