ACP is will designed. It will always be a few features behind the native CLIs as the protocol catches up. But there is very little that you can't do with ACP. A lot can be done with slash commands that are passed through to the agent verbatim.

Python is more than capable of running a TUI. It is just text manipulation after all. Toad uses Textual, which is currently the best TUI library around. I may be biased saying that as I built it...