The problem-Sometimes I want to make modpacks but the version of minecraft I'm playing on doesn't have a compatible version of every mod or resource pack I want, and checking which versions have all the mods I want is a very tedious and time consuming task that ultimately turns me off from playing in the first place

The solution- Add a tab called "mod library" or something similar. You can add however many mods, shaders, resource packs, and other things into the library as you want. When you create a modpack, you have the option to add mods and whatnot from your library. This will direct you to the library where you can select all the mods and packs you want to add. Once you've selected them all, it will then show you every version of minecraft that supports all of those mods, or at the very least as many of them as possible. This will remove the tedious process of deleting a modpack and creating a new one every time you figure out the a certain mod you want isn't available for the version you selected, and it could streamline making large modpacks. I also suggest adding a feature that highlights mods that may clash, as well as notify the user when a mod requires another mod to function