The Odroid N2 is a premium developer board that has all the features you need for digital signage including:
- battery backup RTC
- portrait and landscape mode
- HDMI CEC
- HDMI 2.0 4K display
- 4GB RAM
- High performance CPU and GPU
You can get an Android 9 system image that includes Video Kiosk as the only launcher on the device by clicking here.
Because it is a developer board, the Odroid N2 is not Google Certified. This means that if you need Google Play Services you need to manually install the Open GApps and manually register the device Google Play Services Framework ID.
The primary service that you may need is Google Drive but as an alternative, this build of Android 9 includes Nextcloud which you can use instead of Google Drive.
You can read more about how to install Open GApps on the Odroid N2 here.