Keep the phone unlocked for a preset time.

There is a workaround that may or may not be to your liking. In Settings | Display & Brightness you can set "Auto-Lock" to "Never", and use your Lock button to lock the phone when you are finished needing it to remain unlocked. I never said it was a pretty workaround.

Agreed. There are many situations where 5 minutes isn't nearly enough. I guess all you can do is to send in a product improvement suggestion and hope for the best. I would also recommend posting your design for this new feature here, so that others of us might be moved to second your suggestion.

By the way, I have no idea if it could work, but you might want to look into designing a Shortcut. Create a shortcut that will set Auto-Lock to "Never" when invoked and reset it to a lock interval when you invoke it again. The only gating factor I can think of is if Apple doesn't permit manipulation of the Auto-Lock feature. Good luck.

If you want that your request/suggestion is more incisive, submit it to Apple directly, using this link:

Apple – Product Feedback

Regards

Giulio

"Auto-Lock"