Could I recover pictures from an itunes backup missing PLIST files?
If the backup isn’t encrypted, then the photo files themselves will be intact photo files, regardless of the missing metadata files. (An encrypted backup without the Manifest.plist and Manifest.db would be another, sadder, story.)

Decipher Backup Browser should be able to read the backup without the metadata. https://deciphertools.com/decipher-backup-browser.html If the backup has the Manifest.db, you should see a Camera Roll Gallery section. If there’s no Manifest.db (or it’s an old Manifest.db) use the “Camera Roll Recovery” or “Photo/Video Recovery” sections.