Email or Username:
Have you tried the new ShotOn for Oppo? This is available on the Google Play store and you can check it out here https://play.google.com/store/apps/details?id=com.shotonwatermarkstamp.addshotonforoppogalleryphotos&hl=en
The second one from ShotOn will add watermarks to your images. You can also download this and install it from the Google Play Store https://play.google.com/store/apps/details?id=com.shotonwatermarkstamp.addshotonforoppophotos&hl=en_US
I don't see much of anything else that you'd like or be interested in. I don't see or find any third party tools that would work for you. So sorry.