You've got my attention with the sixel support. I use screen quite heavily, but I'm open to switching for something like that.

I think I use screen in an unusual way, I know a few keyboard shortcuts but 99% of the time I use the command line.

If you press Ctrl-A :, you get a command line with tab completion to access all the screen commands. I have no idea what the shortcut is to split a window, because I just use :split. Same with :resize, :focus, :remove, :paste, :title, etc, etc. I'm quite happy with one less application I need to memorize bindings for, and I'm reluctant to give that up!

Does Zellij do something similar?