iOS supports this with "Guided Access" mode. It has to be enabled in settings, then a triple click will turn it off/on. It can have its own passcode as well. I use it when handing my phone to my kids--start a video, enable guided access, and not worry about who they might inadvertently call or photo they might delete.

I wish it worked more consistently. Maybe I’m just not smart enough, but sometimes triple clicking the side button works, other times it doesn’t.

I wonder if you're not triple clicking quickly enough for the system's defaults? You can adjust this in Accessibility > Side Button

That's an incredible feature that I had no idea existed. Thanks! Now my kids will stop deleting my apps.

I'd love to be able to map this to ipad side switch (which no more exists) - my kids use it to fix the picture on screen so that they could put a paper over screen, and use the picture as a template for drawing.

I can't thank you enough for this comment, it's exactly what I was looking for for so long.

You just changed my life, thank you!

Wow, thanks!

Doesn't sound all that convenient. In truth I just want a hardware switch.

It’s pressing a button three times to enable, three times to disable (with a passcode).

I would say that’s better because it doesn’t take up more phone real-estate, and it can’t be disabled by a smart kiddo.

No, it's not like that at all. You have to not just enable it but also select inaccessible areas of the screen. Every time. And they get greyed out which makes it unusable for watching videos while disabling inadvertent interactions (accidental pause/resume/rewind etc).

You don’t have to disable any part of the screen. Just hit “start” and you are locked into the app. I just tested it and the only thing I could not do was change the volume.

You've missed my point completely. I want the _whole damn screen_ disabled so I don't inadvertently press pause/skip forward when watching videos for example. It's exactly the opposite of the behavior you get from "guided access" thing.

I apologize, I misread what you said. In options (bottom left of the screen) there is a switch to disable touch completely (it also seems to remember it’s setting for that particular app).

There's an option to disable all touches without greying anything out, but I agree that it's too cumbersome to use.

There is an android app called touch lock which I use for this on the odd occasions my 2yo daughter watches youtube/netflix

It's a bit hacky but kinda works (netflix doesn't like stuff floating over a playing video so you have to set touch lock to lock in 10 secs then press play, there's a sort of knack to it. Also it doesn't lock the power button so sometimes that accidentally gets pressed and I get asked why did it stop? :) )

If there are better options out there I'm all ears!

Game Tools on Samsung devices have this feature. For apps that aren't games you need to add them in Game Launcher so the Game Tools button appears in those apps.