steveo68 certainly not as it will only provide up to 3A whereas the laptop you mention may need up to a 3.9A supply I'm assuming MAXIMUM, also with this having an easily adjusted voltage I wouldn't want to be using it on a 19.5v laptop whilst set at anything other than 19.5 as this power supply will do between 9 & 24volts which could damage the circuitry and battery within the laptop

steveo68 the app is available for both android and IOS devices, as for the same device controlled from different users then YES, simply set up the sonoff on one user device and when done simply use the SHARE in the app and enter the details of the other user or users i.e. their registered email address