Here is an article explaining the modern "LetterBomb" exploit, which allows you to load homebrew on your Wii.
The "Levi Loader" is actually , a specialized homebrew software designed specifically for the Wii/GameCube portablizing community. It is the successor to tools like BBI and is optimized for stripped-down Wii hardware that lacks a disc drive. Key Features of RVLoader levi loader wii new
If you are still using an ancient version of USB Loader GX from 2014, you are missing out. Here is an article explaining the modern "LetterBomb"