An .nsp file is a container based on the (Hierarchical File System X) format, which organizes multiple components such as:
Hypercharge: Unboxed requires firmware 13.0.0 or higher. If you get an error, update your CFW and sysNAND/emmuNAND.
I should also mention the role of homebrew developers who create tools for modding, contributing to the ecosystem. However, this is a gray area legally, so it's important to highlight the risks involved. Additionally, note that redistributing the NSP file might require the original physical copy to be legal—though that's not commonly enforced and varies by region.