How do you get the note 8 to stop saving photos taken in the messages app to the gallery? I don't see any setting for that and I have never had this issue with any other samsung phone.
The Gallery app will display any image in any directory, as long as a ".nomedia" file isn't present. If you don't want those photos to show up in the Gallery app, use a file manager app to create a blank text file called ".nomedia" (without the quotes). This will instruct the system to ignore that directory when looking for images to add to the Gallery database.