Sure, Active Oberon is pretty advanced, and Modula-3 had all sorts of things, including generics — but to my knowledge Wirth was not directly in those languages

Sure, Active Oberon is pretty advanced, and Modula-3 had all sorts of things, including generics — but to my knowledge Wirth was not directly in those languages (or with Zonnon or Component Pascal), and he was unhappy with their complexity. (He apparently prefers the entire language's grammar to fit on a single screen.)