Hey bro, I'm a modpack author, I need to use this feature after the modpack is made to prevent other players from accidentally touching the displayed/hidden keyboard keys, thanks.

I am not sure if I understood the request, but if you mean FancyMenu should be able to hide keybind configs in the Controls screen, then no, I will not add that, sorry.

I am not sure if I understood the request, but if you mean FancyMenu should be able to hide keybind configs in the Controls screen, then no, I will not add that, sorry.

Apologies, I did use machine translation earlier, so I'm not sure if the requirements were communicated correctly.
To clarify simply: FancyMenu can be toggled (hidden/shown) using Ctrl+Alt+C. Could you add a parameter in FancyMenu's configuration file to disable this hotkey?

This is already a thing. Enable modpack_mode in the config.
https://docs.fancymenu.net/en/modpacks