If you’ve spent any time in the 3DS emulation or homebrew community, you’ve likely encountered files ending in . These are often "repacks"—highly compressed archives designed to save bandwidth during downloads. However, your 3DS emulator or handheld console won't recognize a .7z file directly.
Use cases:
The most common scenario is that your .7z file already contains a .3ds or .cia file inside. You do not need a specialized "converter" for this; you need an extraction tool. 7z to 3ds converter repack