I got my fitcamx (integrated and powered from the mirror housing) through amazon. Install is fairly easy. It's not the cheapest but I don't want to deal with any wiring. So far as good.
I also have a factory dash cam on a 2023 Merc. The annoying part is that the recording doesn't start automatically and for some reason the dashcam app doesn't show up for a few minutes after I start the car.