It's been ages since I last played with this, but if memory serves once you've created the portable version of NVDA on a USB drive you are free to create a folder for it and move it there and/or create separate folders for other stuff on that drive.
We're not talking about a bootable drive, just a drive that has a portable edition of NVDA on it. In all other respects the drive is free game for storing things in other folders.
I'm sure someone will correct me if my memory is not serving.
Brian - Windows 10 Pro, 64-Bit, Version 1903, Build 18362
The color of truth is grey.
~ André Gide