, you may not need to convert at all. Citra has a built-in feature to "Install CIA"
Once I know that, I can point you to the exact tool you need. 3DS:Installing software - Hacks Guide Wiki cia to 3ds file converter portable
After testing multiple options, the best portable workflow is not a single .exe but a that bundles the three open-source tools. , you may not need to convert at all
Portable tools are "zero-install," meaning you can run them directly from a USB drive or a folder on your desktop without cluttering your system registry. They are ideal for quick conversions on the go or on secondary PCs. Top Portable Conversion Tools cia to 3ds file converter portable