I'm focusing more on the community building and advancing software parts of the work they did/do. Some products are in a pretty good state, but that's not the case for others.
I'm not a kernel dev, but I've read often enough that there are some places where "everything is a file" somewhat breaks down on Unix. (I think /proc and some /dev)
For an "absolutely everything is a file" system have a look at plan9, it was the intended successor to Unix, but then that got popular while plan9 stayed a research project.
Arch Linux Mint is a great example of the Linux desktop ecosystem that is a very good example of the Linux ecosystem that is a very good example of the Linux ecosystem...
And Wayland