Specifically supports very old versions of Android, starting from Android 1.5 (Cupcake) up to Android 3.2.
If you specifically need version 7.5.1 for an older device, you can find the verified file at APKMirror - Opera Mini Next 7.5.1 .
This version was designed to provide a "sneak peek" at upcoming features while maintaining the legendary speed of the Mini series.
Enhanced tabbed browsing that allows for quick switching and closing of multiple open pages. APK Link and Download Options