It is.
Apple has “guided access”, android has “pin app”.
I only have experience with the latter, it works by opening the task management view, and selecting “pin application” on a running app.
That then locks the device to that app. To access anything else, it has to be unlocked as if the screen were locked.
Was definitely on by default on my device.
Personal data is still accessible, if the app you choose to pin is something like the dialer, or your mail app, then yes, you can obviously access contacts and emails. The feature doesn’t block the pinned app from accessing everything it normally accesses.
As for opening other apps, this applies to stuff like links or launchers. If the app has links somewhere, you could open your default browser app. It does not allow you to “escape” the pinned app to anywhere else in the system, unless the pinned app has a way to launch other apps the way launchers do.
The feature could certainly use improvement, but if it were only useful with people you trust, it would be pointless.
It’s obviously intended for situations where you have to let someone use your phone, and don’t want to give them free reign. With people you trust, you wouldn’t need something like that.
It’s far better than nothing, and is in fact part of android.