Short version:
OneDrive Android – Bookmarks feature for PDF viewing: Microsoft are adding a bookmark that makes it easier for you when using the OneDrive mobile app for Android to return to a specific page in a PDF document and pick up where you left off.

Details:
Microsoft are adding a bookmark that makes it easier for you when using the OneDrive mobile app for Android to return to a specific page in a PDF document and pick up where you left off.

This bookmark feature allows you to add or remove bookmarks using the bookmark icon:

You can add or remove bookmarks via the context menu in long-press gesture, whether the press is on text or in a non-text area.

Users can view bookmarked pages using thumbnail (grid view) mode.

Availability:
Microsoft will begin rolling this out to the Google Play Store in mid-March 2021 and expect to be complete by late March 2021.