This app was mentioned in 3 comments, with an average of 0.67 upvotes
Get privacy hider https://play.google.com/store/apps/details?id=com.trigtech.privateme
You can select apps to install and hide here (Kik) and you can change it to look like a calculator and have a pin to unlock
is this the one you're talking about?
https://play.google.com/store/apps/details?id=com.trigtech.privateme&hl=en
It sounds perfect. I think there are others just like this, but I'm not sure how to find them.
edit: won't open like you said. crashes on android 8.
If you got many sensitive apps, do give it a shot!
Most of us may suffer a panic attack when we hand our phone to someone and realize we have sensitive socialising apps, their popup messages, private chats or perhaps have apps installed that we'd rather keep it from public eye. Either way, PrivateMe offers you a better solution, to hide apps into its secret space, moreover it allows you to deal with app notifications, built-in AppLock and cover itself as calculator to make no one can find it and access your secret.