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 - which can have an autocomplete pop up searching their name. Maybe even support adding multiple pubkeys via auto-select like the tag input fields.

Or

CommandB - which can show a new metric pad.