Deliver the mail, though yours is not gold

Question

You pray they don't curl,
part of them likes to be twirled,
and youngsters are thrilled
to give them a whirl.
They be trusty companions,
take you through the Grand Canyons,
or across the entire world.

They got him in trouble,
got him digging up rubble,
though it all worked out in the end;
he rescued a zero,
became quite the hero,
and even made some new friends.

If you like to steal,
then these are worth the deal,
and you can bet you'll get your loot.
When violence follows suit,
and they plead "don't shoot!",
these will aide you in silencing their squeals.

Answer 1

The answer is

shoes

although I don't have all the explanations.

You pray they don't curl,

not sure

part of them likes to be twirled,

Shoe laces need to be tied in a bow ('twirled')

and youngsters are thrilled to give them a whirl.

Kids are excited about getting new shoes

They be trusty companions,
take you through the Grand Canyons,
or across the entire world.

You can wear shoes when walking anywhere

They got him in trouble,
got him digging up rubble,
though it all worked out in the end;
he rescued a zero,
became quite the hero,
and even made some new friends.

This stanza references the novel Holes by Louis Sachar, about a child who is wrongly accused of stealing a pair of shoes and is sent to a detention camp where he is forced to dig holes. Eventually he clears his name as well as the name of another child at the camp named Zero.

If you like to steal,
then these are worth the deal,
and you can bet you'll get your loot.

Shoes can be expensive, and worth stealing

When violence follows suit,
and they plead "don't shoot!",
these will aide you in silencing their squeals.

Still not sure about this part