This is the source code for Advanced Options mod for Doom Eternal Vanilla: https://www.nexusmods.com/doometernal/mods/1255
Another source for the Sandbox version will be uploaded soon but atm, those are 2 different projects.
If you to help making the mod better, please let me know.
15/8/24: This mod started as a experimental project, thus, most of the code is not elegant/efficient. But This codebase will undergo a complete rewrite soon if time allows it.