@JWG82 On your Note 20 Ultra you must have Google Photos configured to backup your Gallery on the Note 20 Ultra. So the photos you see in Gallery just happen to have been backed up to Google photos. It's not that Gallery is showing the contents of Google Photos, it's that Google Photos has a copy of photos that are on your phone being shown in the Gallery.
In Gallery on your S7 tablet it shows the photos that you have taken on your S7 tablet. That Gallery won't show the items in Google Photos because the photos don't exist on the S7 tablet. To see them in the S7 tablet Gallery, you would need to download them from Google Photos to your S7 tablet.
I hear what you are saying, however, I recently took photos on my S7, and they aleady show up in my Note20 gallery, and I have disabled all photo folders from synching though Microsoft. Reason being is because I already pay for google one and I'm cheap and can't bing myself to pay another monthly subscription to have duplicate storage of the same thing
And the photos would then appear on your S7 in your Google photos thru the Google cloud (google drive)