The scenario you describe sounds impractical, unlikely and unworkable, a very edge case "iOS fan family".
Walking out the door with just "any device" that is laying about? Nobody wants that. For one thing, an object like a phone is a personal device, not a sugar bowl passed around and left anywhere.
Your son and daughter will want their own devices, and it makes sense to give them their own devices such as your old phone or cheap phone. For one thing, when you hand your kid your phone you no longer have a phone. Someone might text or call, or the kid will burn through your battery with some game.
This only scratches the surface of what's wrong with your idea.
Walking out the door with just "any device" that is laying about? Nobody wants that. For one thing, an object like a phone is a personal device, not a sugar bowl passed around and left anywhere.
Your son and daughter will want their own devices, and it makes sense to give them their own devices such as your old phone or cheap phone. For one thing, when you hand your kid your phone you no longer have a phone. Someone might text or call, or the kid will burn through your battery with some game.
This only scratches the surface of what's wrong with your idea.