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Hi arlesia,

Such kind of customization officially is not supported in AutoCAD for Mac.
Maybe it is possible to do something by editing AcceleratorRoot.cui in "/Applications/Autodesk/AutoCAD 2019/AutoCAD 2019.app/Contents/Resources/" folder, but I'm not sure exactly.

On Mac you can use:
SHIFT+E - to force ENDpoint OSNAP
SHIFT+Q - to force QUAdrant OSNAP
SHIFT+C - to force CENter OSNAP
SHIFT+M - to force MIDpoint OSNAP
SHIFT+D - to disable OSNAP
I think, that is all.