Does need rebuild Native app after change nanoflow?
If no entity changes, only nanoflow logic change, if necessary to re-build a new version App to re-intall? In other words: When should i re-build a new version Native App(not PWA)?
No, you can just deploy your app and it will download the changes on next time app is started. But for this you must have OTA updates setup from the project navigation.
For details, please check https://docs.mendix.com/howto/mobile/how-to-ota/