Right now there is an extension that provides this functionality, App Hider: App Hider - GNOME Shell Extensions
Previously, it was stated that it could be difficult to add this feature as it could be difficult to “un-hide” apps. The extension mentioned above has a novel solution to this, which is to maintain a list of apps that have been hidden, which allows them to be “un-hidden”, by clicking the trash icon for the app in the extension’s settings.
This list of hidden apps could be somewhere in GNOME Settings, if this were to be integrated into GNOME itself.