I know is probably a dumb question but... does nsz save any space once it is installed?
It does not affect the installed size.
Long explanation:
However, the files themselves can save space. For example, instead of having an .nsp file that has 10 GB size, and your sd card has only 18 gb left, you can't install because it doesn't have enough space, you would need 20 GB or higher save space.
Here is where .nsz come in handy, if you take the example I said earlier, if the normal .nsp file is 10 GB, but you can compress it into an .nsz file, it might lower the size of the file size significantly; let's say from 10 GB to 6 GB.
The .nsz that is on sd card would take 6 GB itself, but the installation size will be 10GB. In the sd card, from 18 GB of space it had left, it used 16 GB of space with the file AND the installed app/game...
Short explanation:
Yes, it saves space as a *file* but not when installed, it is the same size as it non .nsz file.
Hope that wasn't confusing...