Unsolved CRT Custom Resolutions

[JeovaCabrao]

Greetings,

I have been trying to add a custom resolution option to the list of available resolutions on Kodi, but not with a great success.
I have checked all files mentioned under this article from the Wiki, none of them seemed to whitelist resolutions:
https://wiki.recalbox.com/en/tutorials/video/crt/recalbox-on-crt-with-scart-dac

I plan to add custom 16:9 resolutions so I can use Kodi to watch widescreen content with not so huge letterboxes (or even filling up the screen, depending on the content).

Could it something baked inside the OS that cannot be changed since it's BuildRoot-based or am I missing something?

(RPi 4 8GiB + RGB-Pi)

Thank you!