You can type anything in the terminal, and it displays all the matching commands (with help snippets) in real-time

Like when you start typing something and press tab for autocomplete options (on a Mac at the moment but PowerShell does this too IIRC)?

Then, if you type a command, it displays its help (snippets around the words after the command).

If I understood correctly: I'm imagining something similar to many code editors when you type `someFunction(` a popup appears with the arguments, their types, and a docstring if the function has one.