For those of us who grew up thinking that UNIX, in some (elusive) form, was the Holy Grail of operating systems, NextSTEP was where we wanted to live, work, and play, as soon as we knew about it.
In a small way, the internet was 'late' for me - most of these kinds of development weren't happening on the internet yet. This, in particular, was a Steve Jobs project, and was spoken of only in whispers and sometimes in a magazine interview. By the time I really knew anything about the technology, it was pretty much reliquary. This applied pretty much to all of the Unix world.
Like all the rest of it, Linux was a bit late getting to me as well, in that sense that I had just began to steel myself to the realization that I had missed the heyday of open architecture, multiuser operating systems, and would be saddled with some kind of M$ Windows for the rest of my life.
Of course, that's all highly subjective, and truth be told, I was just about as ready for Linux at that point as Linux was for me, and a million other screwball wingnuts like me -- our ship, as it were, had just landed, and was recruiting crew.
There are a few things from back then that were worth retaining from the museum depository. Some of those that have perhaps been easiest to keep in play and updated are window managers. Openlook is an oldie but a goodie, and modernized (OpenBox WM), it is more powerful than ever, and running with critical efficiency on the Raspberry Pi, where it makes it possible to use a Pi4x8GB like one might have used a workstation of yesteryear.
Now NextSTEP has been shown the love, and here it is. It should run on the Raspberry Pi as well, and given that the project has a Debian target, I'm willing to bet it will run just fine.