So your data is only on your computer. Fully Private. App will have no outgoing connections.
Resonates with you? then:
Please vote here which app you would like me to start with:
https://www.supermakers.club/vote-for-safe-apps
If you are curious on how I came up with the idea, read here the full story on my profile's featured post. (IH is not allowing me to post another link here)