https://en.m.wikipedia.org/wiki/Acorn_Computers
You can run RISC OS on a modern ARM like the Raspberry PI - it gets weirder the longer you work with it - menu items with input boxes and other GUI widgets, a strange DOS VMS UNIX hybrid CLI that appears at the bottom of the framebuffer, scrolling your graphic screen up as you type and full of terminology that's incredibly excessively British.
Go to 10 minutes to see the shell https://youtu.be/oL4w3AK6Qpw?si=Vdu2ur1fM0N9Tl2X&t=10m and http://www.riscos.com/support/users/userguide3/book3b/book3_... for the documentation
Also see 8:50 for the British terminology and 12:34 for an example of the weird menus
The thing I like about it is the creators clearly knew what the dominant paradigm was and made a decision to be different. It's nice.