I know about the theme, i'm using Window Maker which uses a theme closer to NextStep and occasionally i hack on a toolkit[0] that has a Next-ish look (and feel, to some extent).
However i meant stuff like the desktop metaphor (Macintosh also had one but Win95's approach was more popular and mimicked in other environments), the start menu, the taskbar, etc, some newly introduced controls like tabs (i think OS/2 had tab-like controls/containers but they worked differently to those in Win95 and nowadays pretty much all tabs work like in Win95).
The use of recessed surfaces for displaying information and the rectangular buttons were very NeXT-like, but more compact because it needed to work at VGA resolutions, but I don't think they managed to capture the essence of their framework which is, impressively, still alive in every Mac sold.
I wonder how hard it would be to get NeXT source from the 1990's and compile it on macOS 26.
However i meant stuff like the desktop metaphor (Macintosh also had one but Win95's approach was more popular and mimicked in other environments), the start menu, the taskbar, etc, some newly introduced controls like tabs (i think OS/2 had tab-like controls/containers but they worked differently to those in Win95 and nowadays pretty much all tabs work like in Win95).
[0] https://i.imgur.com/yaU5OLn.png