Were notebook interfaces (like jupyter & mathematica) not, in practice, so reliant on web-tech, they'd be a good heir to the command line / REPL lineage (in line with the mouse-aware command line that, ex., plan9 has).

On the more general TUI side, a curses frontend for TK exists (though a TK frontend for curses doesn't, AFAIK, even though it'd probably be easier to write & more complete). TK is just about the smallest, easiest-to-use, and most cross-platform GUI library, so if you want to move existing curses applications to real widgets, TK is the ideal target.

The unix terminal is a clusterfuck of technical debt, and while curses exists primarily to abstract that away, it still leaks. Basically all non-trivial TUIs are dependent upon terminal behaviors that ought not to exist anymore, and this holds back attempts at modernizing the unix terminal (like kitty at the near end and terminator at the far end), locking us into hacks like abusing control characters for indicating URLs, performing text processing in the text rendering facilities, etc.