Can I deny it Internet access?
Announcing Amber a android application Nostr signer.
With it you can have your nsec on only one application and use your npub on every other android application.
Instructions on how to add support for amber in your application are in the read me.
https://github.com/greenart7c3/Amber
Will try to add support for it in amethyst next week
cc nostr:npub1gcxzte5zlkncx26j68ez60fzkvtkm9e0vrwdcvsjakxf9mu9qewqlfnj5z
Discussion
If you want to just sign the event and copy the raw json to send it with other client you can deny the internet access