Cuis [1] is a simplified fork of Squeak, trying to make it more closely resemble the original Smalltalk-80 (while using a custom version of Morphic). Squeak itself initially tried to not be bound by Smalltalk-80 heritage. Now, it focuses on preserving of the experiments that Alan Kay, Dan Ingalls, and others did, being very conservative in this regard. Pharo forked to have a system that can actually evolve.

Pharo should generally work on Wayland, so there will be more things going on, probably.

[1] https://cuis.st/