That’s a great question. Speaking from experience of my two daughters and having gingerbread parties with their friends...... decorating is much more relaxed than assembling a house. With kids I have found that more time is spent placing the candy versus applying the frosting. The may dab on the frosting or apply a glob, and then choose and place candy. They aren’t constantly squeezing the bag as when assembling the house. And kids don’t normally do much decorative piping.
For the younger kids age 4-5, depending on the skill....I’d probably use a bowl of frosting and a plastic knife.
For the older kids I’d use a disposable pastry bag and rubber band to close the ends. The disposable bags are fairly thin, helping to reduce hand fatigue. Also making the Royal frosting a little thinner/stickier will help.
I prefer disposable bags that are manufactured flat versus on a roll. I’ve torn bags when trying to separate from the roll.
When it comes to ground cover, if applying a blanket of snow (frosting) FOR ANY AGE I provide a fresh batch of frosting in a bowl with lots of plastic knives. No sense experiencing that hand fatigue trying to get enough frosting for ground cover.

I’ve never used squeeze bottles. I’d think that would create more hand fatigue since over time the bottle may be more difficult to squeeze in general since the plastic is stiffer? Plus I wouldn’t want the cleanup of plastic bottles.

Hope this helps.
Loreta