I'm 2 months late to this conversation, but everything @NaniNekoChan said is absolutely relevant. Go look at the Steam page. There is no way to purchase the game. THE GAME IS STILL NOT OUT. The release date at the top of the page says "TBA" which mean "To Be Announced" in English.
Gunsmith Simulator Gameplay 4K Simulation PC Early Access
https://i.imgur.com/yBkyjf3.jpeg