Kitty is a magnificent piece of software that has radically enhanced the interface between me and my computer. And it does this while consuming negligible resources.
I also use its shell integration features, such as putting the scrollback into a pager, constantly.
if you are thinking of tmux then the problem here is that tmux is in itself a terminal.
to get session management away from the terminal it would need to be done in such a way that when the session tool connects the session it merely acts as a proxy or less, but does not interpret and then translate the signals that come from the session like tmux does.
this is not trivial, at least with the current way terminals work.
we need to entirely rethink the terminal protocol: https://news.ycombinator.com/item?id=47941354