I own a bunch of Glocks, and some of the triggers or trigger safety levers ARE a little annoying; rough at the tip, or having sharp edges or mold flashing that abrade the finger. I have doctored some of these by using strips of fine sanding cloth/paper to remove the sharp edges, but I have NOT reduced the protrusion of the trigger safety lever through the front of the trigger. The trigger safety must be fully depressed to allow the trigger to begin moving to fire the weapon, and if a person were to reduce the protrusion of the safety through the trigger to get the flatter profile you describe, this might cause a failure-to-fire problem under less-that-ideal-grip-on-the-pistol situations.
There are a handful of aftermarket trigger options for Glocks, and I do remember seeing one that was aluminum and had a larger/flatter trigger safety lever, which might give you a feel comparable to your SIG (I have no experience with these, sorry). However, I have replaced the grooved target-style triggers in my smaller Glocks with the smooth/rounded triggers from the full-size guns, and I do like the smooth factory Glock triggers much better. Even some of these required minor smoothing to remove sharp/rough edges on the safety lever or trigger tip itself.
"Placement is power" -- seen in an article by Stephen A. Camp
(RIP, Mr. Camp; you will be remembered, and missed)