Which method of monetisation is preferable for mobile applications?

Please consider it from both a user and developer stand point.

My idea is cryptomining with the following points:

1. The user would be notified of what's happening and get to set the intensity (5-30%) of CPU usage. Therefore doesn't drain battery more than games or produce excessive heat.
2. The mining would only be active when they use the app.
3. It would be crypto-mining only, not coupled with any other options/monetisation methods.
4. All of the users data still remains secure and doesn't leave their device.
5. The app is still fully functional in offline mode.