Not ironically this would mess up granny and granddad when they activate it accidentally.

iOS has Guided Access which should accommodate what you’re trying to do.

I’m sure android has something similar too.

I want this, but not just for toddlers, just for handing over my phone to anyone really. Put on some media (photo, slideshow, video), lock your phone inputs, hand it over to someone else to look at, without having to worry that they will invade your privacy as a prank.

Whatever the method of unlocking the screen is, the kids will learn it

My old phone had a setting for this but it seems it's part of OneUI so Samsung only :/ It's called Interaction Control in Accessibility Settings.

Yes. My niece is alredy 4 but she discovered all the amazing filters. I cant have 1 video call without her taking the phone and using all the filters. Headache inducing

On the other end, they need to move the camera to the bottom of the screen so people with bifocals stop using only the bottom third of the camera.

Or you just parent them properly.