Need Advice

I’m new to the world of gun ownership and I made a mistake when purchasing my Glock 19 Gen 5 through an FFL. I want to put a red dot on it and accidentally purchased the non mos version. Now I have a great gun that’s never been fired but can’t do what I want.

I’m weighing the pros and cons of trading it in and using the money towards a Glock 19 Gen 5 MOS or getting it milled. I know this voids the warranty for the slide. How worried about that should I be? I have a Holosun HS507C.

I have the money for either option. If you were in my shoes, what would you do?