Just let us explore this for a moment.

Which Lisp Machine is GNU Emacs emulating? Actually existing ones or a conceptual model of a 'Lisp Machine'?

If we look at the existing ones, there were two main ones: Interlisp-D based systems from Xerox and the MIT Lisp Machine and its later variants from LMI, Symbolics and TI. There were a bunch of lesser known ones, which didn't have much influence. Both the Xerox Lisp Machine and the MIT Lisp Machines have emulators - they allow you to run them usually on some Unix/Linux + X11. None of them had any sophisticated terminal capabilities - all were needing/providing a full GUI environment.

If you boot a Symbolics, it starts into a GUI environment with a Listener as the console. This Listener is not an editor window and it is not text only - it supports full graphics and mouse input. The listener runs commands and Lisp forms. The commands are providing typical servives like a login command, listing directories, copying files, enabling and disabling of network services, reading tape drives, compressing files and more. Editing files is usually done in a text editor, which is actually an Emacs called Zmacs. Applications are usually fullscreen windows with subpanes. These subpanes are arranged by layout descriptions provided by the application. But the window system is actually also providing the ability to have overlapping windows or multiple windows on the screen or even windows composed of subwindows. The implementation of all of this is heavily object-oriented using something like Flavors, New Flavors or, later, CLOS.

If you look at GNU Emacs, it does not provide a GUI-first environment, its basic abstraction is the text buffer and a UI representation of that in a terminal or a window. You don't login into GNU Emacs. Its programming model is different, since it doesn't use OOP at its core. It's not multithreaded.

The main similarities to the MIT Lisp Machine OS: they appear to be text-based (which the MIT Lisp Machine uses a lot, but in different ways and mostly not editor-based), there programming and extension languages are variants of Maclisp, they provide things like REPLs, Lisp code execution, Lisp debugger, Lisp interpreter, etc... But all the latter is also provided by Multics Emacs written in Maclisp in the late 70s. These are not features of a Lisp Machine, but generally the features of a typical Lisp system. The Lisp Machine extended this with real GUIs, real OS code written in Lisp (like serving network interfaces, event handlers, frame buffer interfaces, file systems, process schedulers, dumping memory to create worlds which can be booted into, ...)

The main reason the Lisp Machine existed was that they were a fast track to personal workstations for AI programmers/researchers and the groups knew Lisp, it was a good prototype environemnt for them, and they could built such personal workstations within a few years.

But interactive Lisp systems existed before and after. Before usually on 'mainframes' (see Interlisp with its terminal-based tools) and after that on many types of machines: like UNIX workstations and Windows-based personal computers

Now: what parts of GNU Emacs make you think that it emulates a Lisp Machine? Is it emulating real existing ones or parts of them? Is it emulating comcepts? Concepts which probably existed also outside of Lisp Machines in interactive Lisp systems?