Sorry for the slow response - I was on vacation.
I believe that is true. However, each of these instances is separate - they do not share memory. We might be able to get them to communicate via web sockets or something, but it's not the same as having a single Newspeak process with multiple native windows (we had that with the Microsoft Windows native Hopscotch UI on top of Squeak - that still runs, but is long obsolete).
One can also set up a "tiled window system" in the web UI.
In any case, this is currently a low priority item. Of course, if you want to work on something like that, let me know and I'd be happy to discuss. Or if you are happy with the PWA - well, that's great, that's why we did it. Various refinements to the PWA would also be nice.