I have switched from Google Pixel 4 to Samsung S20 a couple of days ago. I did the ususal transfer from one to the other.
I have a lot of music and a lot of photos, both of which were respectively kept on Google Photos and Google Music Play. None of the music copied into to my new device (that I understand) but the story with photos is slightly more frustrating.
I have noticed that the Google Photo app copied over and had all of the pics as it should, however only very few were showing in Samsung Gallery. Since I have around 17000 images it took mi hours downloading them all to my PC so I could manually add them to my new S20, only when I tried it I had a message box pop up to say that this image already exists in the destination folder!!! I am really upset and angry because I cannot quite understand what is happening.