This mobile app does largely what Adobe PDF Scan or similar apps do, but your scans stay private and offline.
It runs on Android and iOS, with the Android app being available from a variety of sources. It is open source without ads or tracking. It has been translated into 40 languages already.
Features include scanning, document enhancement functions, PDF export, auto edge detection and OCR support. Not only that, but it can also optionally sync via WebDAV to your own cloud storage such as Nextcloud.