We do not collect and save any of your private data by ourself with one exception: when you activate notifications for one account we will save a mapping between the Address in question and a FCM push key to send you the push. Your private keys, which are generated by WALLETH (via geth) are only stored locally on your device and are never shared automatically. You can manually share them if you wish (e.g. to transfer them to another device).
Information like balances, transactions and other Ethereum related information are part of a public available and distributed ledger called the Ethereum Blockchain.
WALLETH is interacting with Etherscan - you can find their policy here: https://etherscan.io/terms
On Google Play WALLETH is using Firebase. See their policy here: https://www.firebase.com/terms/privacy-policy.html If you do not want to use Firebase - please use the version from FDroid or compile it with the noFirebase flavor yourself.
If you have questions or suggestions - please contact us! http://walleth.org