TUIs would be great if they didn't have to render all text the same size, for me that's the main win with GUIs, you have total freedom with what you can do with your pixels.

I would definitely be pro minimalist unicode-character-themed GUIs for what it's worth. Where every graphical primitive is basically a unicode character, without the restriction on font size.

That's not total pixel freedom, you're still limited to text

Some terminal emulators, for example Kitty, can render text at various sizes (within the same window).