Microsoft is finally planning to add an offline mode for files to its Teams app for Android. According to the Microsoft 365 roadmap, this update is currently under development, and it will be available on the Google Play Store in June 2021 (via Windows Central).
The new Offline experience will enable mobile users to make all their previously opened files accessible offline. To do this, the user will need to tap the “Make available offline” option available in the three dots menu (...) next to the file to keep its downloaded version. A notification will then appear at the bottom of the screen informing that the file is now available offline, and it will be removed after 14 days of inactivity.
The new offline mode should make it easier for users to keep track of all their important files without an active internet connection or in bad network conditions. However, the feature is only coming to the Microsoft Teams Android app for now, and it's not clear if or when it will make its way to the desktop and iOS client.