So, a Glock is a Glock, is a Glock...Right?
I'd be very careful buying an aftermarket Glock trigger from a business without liability - In general. I've never heard of Johnny Glock...I personally use Overwatch in every pistol I have.
To take that a step further, you should be completely aware that in any self defense situation, a trigger modification of any kind, will be used against you in the court of law.
For example - Say you did a trigger job to your own trigger.
After an incident, your pistol is taken to an armorer who assess the status of the weapon. He notes a trigger job, lighter or heavier and what was done to the firearm.
Now you're in court after said incident - Armorer/Glock expert testifies that you had work done - You lightened the trigger.
Other side now takes you to task, asking if you're an expert or an armorer, if your modification was necessary, what it's purpose was...Ultimately they now claim you modified your trigger for tactical purposes and you're an evil monster.
I would never purchase a modified stock Glock trigger - EVER.
If you're going to buy a trigger, ensure it's the way you want it as it sits and purchase it, as it sits.