Sounds like you are using multiple member profiles. This allows each individual to access their Apple Music/iTunes features. However, iCloud Photos (and Game Center) are not part of that. To access her iCloud Photos you'd have to log out the "main account" and then sign in with hers (Settings > Users & Accounts > iCloud). From the ATV User Guide: https://support.apple.com/guide/tv/share-apple-tv-atvb0753b37d/tvos
Sounds like you are using multiple member profiles. This allows each individual to access their Apple Music/iTunes features. However, iCloud Photos (and Game Center) are not part of that. To access her iCloud Photos you'd have to log out the "main account" and then sign in with hers (Settings > Users & Accounts > iCloud). From the ATV User Guide: https://support.apple.com/guide/tv/share-apple-tv-atvb0753b37d/tvos