Also worth mention is Simple Gallery Pro.
https://f-droid.org/en/packages/com.simplemobiletools.gallery.pro/
Files can be hidden and then password protected.
Unfortunately, these files are only hidden well from the app itself, and the related file manager (Simple File Manager Pro).
With a little know how, they can be found with a typical file manager.
Keep in mind that this has still been enough to keep nosy busybodies at my work from getting into anything.
But Anemo seems even better to me, especially if I use my launcher (KISS) to hide the Anemo app from view.
This means that the app icon will not even show up at all unless a setting in my launcher is changed.
KISS is a very odd (but excellent) launcher, and most folks have not even heard of it.
It is totally different from other launchers, and as such makes my device exceedingly strange for anyone else to navigate.
The launcher actually takes only a short time to learn, but this is more than enough to keep others at bay.
https://f-droid.org/en/packages/fr.neamar.kiss/
Note that many launchers have the option to hide apps, but having an oddball like KISS is also great for security.
