How to add other stuff while making custom mods for opera gx

So i have made a custom mod for opera gx using the file provided by github of operagx. But it only provides customization for Shaders, wallpapers, themes and the sounds. But i also want to customise things like app icons, splash screen and stuff but i dont know how to do it as the existing manifest file and mod templeate folder doesn't have code for all this stuff. Can someone help how to add the other elements pls.