A new update to the Google Backup & Sync app for MacOS and Windows 10 is rolling out that brings a lot of fixes and a few new features. The updated build is version 3.39 for those keeping score at home. This new build was released on February 1st so it is likely that you already have it installed as Google pushes updates to Backup & Sync behind the scenes.
For those who use Network-Attached Storage (NAS), this update is an important one for you as it is finally supported. You can now backup files and folders stored on a NAS to your Google Drive. The folder has to be mounted and you will be able to add a NAS folder from the My Computer section of Google Backup & Sync.