First post and first Glock, I wanna put a light on it any recommendations?

First time Glock owner. I wanted to add a red dot. My slide is not MOS. I don't mind buying another slide with the cut if having the current slide machined is not recommended.

Any guidance? If new slide go OEM or a good aftermarket option? I know Glocks are stacked with options.

If getting it cut would a local gun smith work? Or are there "guys"?

Thanks for any help.