I want to use a full stovetop griddle in my regular stovetop. I have this https://www.webstaurantstore.com/vigor-23-x-23-portable-steel-griddle/247PG2222FH.html My issue is that the heating ends up being uneven hot in the spots where the burners are and cold elsewhere. Is there someway I could get even heating across my entire stovetop? I have a regular residential gas stove. I’m trying to cook large amounts of scrambled eggs and hash browns at once.
Well, you'll never get the entire griddle evenly heated. But this griddle is pretty thick (3/16") so the results will not be too bad if you allow the griddle to preheat for a long time (at least 30 minutes). You'll still have hot spots and less-hot spots, but there won't be any 'cold' spots.
You're going to have to learn how the griddle performs and how to move the food to different zones to cook it the way that you want.
As a side note, even in commercial kitchens parts of the griddle are hotter than others. This is quite useful to cook two things at different temperatures, or to move something that is already cooked to a less-hot spot while another component of the dish finishes cooking in a hot spot.