You can lend your aid to another creature in the completion of a task. When you take the Help action, the creature you aid gains advantage on the next ability check it makes to perform the task you are helping with, provided that it makes the check before the start of your next turn.
Alternatively, you can aid a friendly creature in ...
No, it's not a loophole. On their turn, PCs either Attack or Help
On your turn, you can move a distance up to your speed and take one
action. (Basic Rules, p. 72)
Actions in Combat
Attack, Cast a Spell, Dash, Disengage, Dodge, Help, Hide, Ready,
Search, Use an Object (Basic Rules, p. 74 & 75)
Pick one, unless a game ...
A creature can't Help a turret
The Help action states it is used to aid creatures (emphasis mine):
Alternatively, you can aid a friendly creature in attacking a creature within 5 feet of you.
And the artificer turret is not considered a creature, but an object:
The turret is a magical object that occupies its space and that has crablike legs.