You can manually download the RPM from Gitlab or install via Chum to automatically get updates.
For Chum, see GitHub - sailfishos-chum/main: Documentation and issues and Announcing sailfishos:chum .
From the data above, the app currently doesn’t work on the XA2 (yet). Please let me know if it doesn’t work for you!
In general, the functionality is similar to Battery Buddy, only my approach is different (more in the direction of less complexity/overhead and therefore less features).