Does the HORIZON 30 Series support USB flash drives and external hard drives?

Yes.
The HORIZON 30 Series supports USB flash drives and compatible external hard drives.
Supported storage
- USB flash drives
- External hard drives below 4 TB
Note
The time required to detect an external hard drive depends on its capacity and the number of stored files.

Supported file systems
- FAT32
- NTFS
Note
Google TV does not include a built-in file manager.
To browse files on external storage devices, install a file manager from the Google Play Store.