Not really.
There are the mirror cameras, which are probably the most suited ones as most of those have a larger screen in a place you can see it..
And some of them actually have reversing camera functionality.
But the main issue with using dashcam as a reversing camera are placement.
A dashcam ( front or rear ) are best put up high on the glass, and facing almost level towards the horizon, so this is fine if you have a van or a SUV style car with a fairly flat rear end, but if you drive a regular car ( sedan ) it will have a boot, and it could hide a child playing behind the car.
Also dashcam rear cameras don't have the guide and distance markers reversing cameras have, and often you cant mirror the image so the image on the screen go right when you reverse your car right.
And also most dashcams have tiny screens, and placed ideal ( in front of mirror as high as it can get, then most often you cant even see the LCD screen, also dashcams dont have the LCD screen come on when you put car in reverse, and they also don't switch to that camera automatic.
I have a lot of cameras in front of my mirror, and really from my seat and with my 6 foot 2" height i can see them ( above mirror ) but the screens are sso small, and also hard to read in sunshine ( they dont put high quality LCD or AMOLED screens in dahscams )
But how it is of course depend on a lot of factors, i am fortunate my windscreen are all clear of stupid sensors ASO, and my mirror are mounted off the roof and not the windscreen.
And i have a dotted area onto which most of the camera sit so its only the bottom 1/3 of it you notice from the outside.
You are much better off buying a true reversing camera, one of those with a 5 - 7 " LCD screen you can get for 50 bucks i reckon, and its camera you can put down low where no child can sneak under the radar so to say.
I drive a tiny Jap 5 door hatchback, that have its hatch that are pretty flat and vertical aside for a couple of degrees, still the first couple of feet behind my car i can not see in the footage.
My car after it got molested by a 4x4 driven by a phone junkie. ( 1 car between me and the 4x4 )