How to prevent USB Block Policy to be circumvented?

I know that I can disable USB devices using group policy for the computers of my company. What I want to achieve is allow user to use the USB port only for charging their phones, connect their mouse and keyboard but NOT allow file sharing from removable media to computer (and vice versa). So my question is how do I ensure that this policy works if:

  • Some of the users have laptops, and in some cases they work from home and are not connected to domain
  • Some of the users are local admins to their computer

Thank you