I know this feature is kinda frown upon but I really hope to see a standard way to really switch between multiple fonts in a terminal, not just playing with variations. I'd really want to try the Monaspace font familly so I can make a distinction between my input and a program output and it's error output by using different fonts. It could also allow the use of these fonts inside neovim for instance for richer code hints.
Kitty does allow you to choose 4 different fonts for regular/bold/italic/bold+italic. I guess that with the right configuration it should be quite straightforward to set your shell to use bold+italic for your input, and set that as a different font. sure, that font will be used for other bold+italic text, but that's quite uncommon.