I'm sure there's a proposal for this somewhere, but I've always wondered if it wouldn't be most viable to just have a separate "reader mode" that replaces all the TUI elements with some sort of templated descriptive string of text, something like "Page one. Foo entry. ' bar'"

Seems a lot more viable than trying to get new standard escape codes and outputting those along with visual content that may be flickering erratically. Also probably gets too complex faster than those proposals with more intricate UIs, but IMO it's really hard to defend TUIs for anything but relatively simple programs as an in-between a CLI and a native application.