What I’ve read about Lisp machines[0] really piqued my interest.
Haven’t tried one yet though.
NeXT’s computers[1] also seems very cool. Haven’t tried them either but I’ve used both WindowMaker and macOS.
WindowMaker was never a clone of NeXT—it was more of a cool window manager that just happened to superficially look like NeXT. If you want to play with a real attempt to recreate a “deep down” NeXT clone you want this: