Will motion, multi-purpose sensors and siren work if electricity and/or internet is out?

[sidjohn1]

If the smart lighting smartapp can’t turn the device on/off then only your hands can in the event of Internet or power failure. Even the ST iOS/Android/Windows App requires working Internet and does not run locally.

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How to know Local App vs. Cloud App in Hub 2.0?

For the first two questions. May be some v2 owners can answer all of them. I don’t think you have to push anything on the hub to run locally. https://graph.api.smartthings.com/localInstalledSmartApp/list