How to prevent screen lock while on photos?

So I have this issue when a friend/family members ask me to show them a photo from the gallery or from another app, they take the phone and swipe through the entire gallery before giving me back the phone. I want to create a shortcut to limit their access to a few seconds before the screen locks. Like setting a timer before I give them the phone, so that they only have a few seconds to look at the photo, when the screen locks, they wont have a choice but to give back the phone.

I know that I should do this in the shortcuts and set a timer and screen lock but however I do it, it doesnt work. Any help regarding setting up the shortcut would be appreciated.

[Re-Titled by Moderator]