You don't have to scan a PNG, it's already a raster image. All someone would need to do is download the PNG, or transfer it in some way to their device, such as via email or a file sharing site like dropbox or similar. It's a digital image file format, and as long as the file itself is not changed it will be the exact same file with the exact same colour values.
However scanning a printed version of a digital file will NOT get you the same results. Also, uploading a PNG image to some image sharing websites might result in the file being converted to a JPEG, which again will change the file and add compression, so all bets are off.
If instead you mean to screenshot an image, it's also not the same as having the original image file. So again, not the same file, and not the same result. There's no telling what the results might be since it would depend on the device. And so, all bets are off again.