Currently, the OneNote app for Android does not support opening multiple notebook pages simultaneously within the app. You can only view one page at a time. However, you can switch between pages by navigating through your notebooks and sections. If you need to reference multiple pages, you may consider using a split-screen feature on your tablet, if supported, to view OneNote alongside another app.
References:
- Multiple account access to Copilot for work and school documents
- Your Phone
- Your Phone
- Work side by side with other apps
- Open the OneNote client
- Announcing Your Phone multi-apps experience—Interact with multiple Android mobile apps at the same time on your Windows 10 PC
- Optimize Power BI reports for the mobile app