There are bluetooth screen lock utilities that allow one to auto-lock and unlock the machine based on the signal strength of whatever Bluetooth device you pair

There are bluetooth screen lock utilities that allow one to auto-lock and unlock the machine based on the signal strength of whatever Bluetooth device you pair it with. I would look into the hands-free Bluetooth speakers (meant for auto use) with a Wheelchair power to USB convertor (most likely the easiest would be via an auto 12V DC adapter). That way you can have a mic/speaker mounted on the wheel chair to control the machine as well (if you don’t have a wireless mic already). Any Bluetooth device capable of being paired will work though. This will prevent someone going through your laptop while you are away. I actually have one I use on occasion at coffee shops called Bluetooth Screen Lock available on the App Store, but there are other free and low cost apps that do the same thing available. The on I use allows me to set the sensitivity so that it will lock after being about 6 feet or more away, and unlock when I am within that distance. I can also set it to lock at the maximum BT signal range as well.