Cross-Platform User-Defined Keys?

If I use InputManager, then users can only change keybindings on platforms like Windows?

If I want users to be able to define keys on Android, then InputManager doesn't work? For example, they have a keyboard or controller and want to remap the default input via InputManager.

So the only way to do this is to use a library like cinput? Or I have a massive switch/if section in my Update function, where I check every possible key (which is essentially what cinput does)?