@KarKar: I recommend using Smart Switch to transfer your photos from your S9 to your Tab S8+. If you check the Samsung folder in the apps drawer of both devices then you may find that it is already preinstalled, however if it isn't then you can download it from the Google Play Store or Galaxy Store.
What is Smart Switch and how do I use it? | Samsung UK
I understand that you'd prefer not to use Google services to transfer your content, however it couldn't be simpler. On your S9, head to Settings > Accounts and Backup > Backup and Restore > Google Account > Backup My Data, then you can backup your photos and videos to your Google Drive account. If you would like to double check that the photos/videos have been backed up, then please swipe up from your Home Screen > Google (folder) > Photos. Now, if you register the same Google account to your tablet, then you will be able to access your photos via the Google Photos app. Let me know how you get on.
