An NSP is a Nintendo Submission Package. It is the file format used by the official eShop. If you have a modded Switch, you can dump your digital copy of Tears of the Kingdom into this format to back it up or run it on PC emulators (Ryujinx / Yuzu).
What mods are you running on your dumped copy? I just got the "Weapon Durability Remover" working on 1.2.1. legend of zelda tears of the kingdom nsp
Nintendo Switch (CFW) / PC Emulation