I love the ideas of Smalltalk and Lisp machines too. Do you know of anything promising in that area? (other than Ink & Switch)

Are you using Pharo already? If not, give it a go: https://pharo.org/

For taking notes and stuff you'd otherwise do in Jupyter or Livebook, try GT: https://gtoolkit.com/

It's not an OS, but you can just abstract over OS actions within either and keep them as your main interface, similar to how some people rarely leave Emacs.

https://newspeaklanguage.org/ ...?