PPSSPP on Linux external device

[E_Carver]

By default, the emulator opens a folder similar to the usr/home folder for Mint. Click on the arrow until you see directories like [boot], [root], and [mnt]. This is about as high up the directory tree as you'll get and there should be a [media] folder. Click there and your username should pop up, and clicking there will bring you to your external storage device.
Confusing, yes... took me almost an hour to figure it out.