That's a pretty good feature request. I would tag this so that the app developers can find it more easily when they are looking for community feedback and feature suggestions.
In the meantime I'm sure you're familiar with the gallery apps option to hide albums. The kids probably are too.
Knox Secure Folder works well for that. I've set it up a few times to see how it works. The gallery is there as a default. The pictures I added don't show up in the main gallery app and we password, pin or biometric protect them.
There are also some apps like file managers ect in the play store that might be able to do that but I prefer to use Samsung or Google for stuff like that.
Agreed! I don't know why this isn't an option when it's definitely needed. I wanna be able to show people a picture or pictures without accidentally showing something I don't want them to see 🤦🏾♀️