That’s how discord and telegram bots do it today. Autocomplete is hard because mobiles don’t have a tab button on the keyboard.
I have a few bots and they fallback to a cli like help text for unsupported commands or input errors.
I don’t know if a special command selection UI could work (adoption would be hard), however if you brought a way to dynamically generate forms that can be supported it may be cool.
Examples
CommandA
Or
CommandB
