Would an electronic main shutoff still work without power or Wi-Fi?

In a hypothetical outage, an electronic leak-detection shutoff raises two separate questions for me: can the valve still be closed manually if its power source is unavailable, and what happens to alerts if the internet connection drops?

I wouldn’t assume every system depends on Wi-Fi to close the valve, or that a battery backup keeps every feature running. For emergency readiness, which matters more to prioritize: a clearly accessible manual shutoff, backup power for the valve, or knowing how the system behaves when it loses connection?