KDE Connect

Website
Extremely useful Open Source Linux ecosystem tool from KDE folks, though Mac and Windows can use it too. Allows connected devices to:

• Receive your phone notifications on your desktop computer and reply to messages
• Control music playing on your desktop from your phone
• Use your phone as a remote control for your desktop
• Run predefined commands on your PC from connected devices.
• Check your phone's battery level from the desktop
• Ring your phone to help find it
• Share files and links between devices
• Browse your phone from your desktop
• Control the desktop's volume using your phone
• Send SMS from your desktop

Only major limitation is LAN or Bluetooth requirement; so unless the user is spoofing, there's no remote connectivity.

Useful either way, still buggy though.

Works across:

• Desktop computers
• Mobile devices
• Portable gaming devices