VitruvianOS – Desktop Linux Inspired by the BeOS

https://v-os.dev

VitruvianOS

Vitruvian is the human-centric Operating System.

If you like BeOS, take a look at Haiku https://www.haiku-os.org/ , it's very nice and very usable system based directly on BeOS.
Haiku Project

Haiku is an open-source operating system that specifically targets personal computing. Inspired by BeOS, Haiku is fast and easy to learn but very powerful.

Haiku Project
And much better option, running the real deal, instead of some compatibility layer.
Presumably there's a lot more modern software written for Linux which you'd end up running through a compatibility layer from Haiku? The better option seems relative. I could be misremembering how Linux programmes are handled on Haiku though.

Maybe the fallacy is not exploring what a given OS is great at?

We don't need to clone UNIX all over the place.

How strictly do you mean “UNIX clone”? Because Linux isn’t strictly UNIX. But then at the other end of the scale, BeOS was also partially POSIX compliant and shipped with Bash plenty of UNIX CLI tools.

Perhaps it’s better to play it safe and just run DOS instead ;)