I don’t recall there being a successful Emacs port to classic Mac OS — I would have been very interested in the early to mid 90’s. The Mac editor landscape was actually pretty sparse if you wanted something sophisticated/integrated/customizable. There was Alpha, which was Tcl-based. MPW’s editor wasn’t customizable to the same degree. BBEdit existed, but it was actually quite bare bones at that point; even today it’s still pretty fixed-function.