Is anyone aware of an app that allows an orderly shutdown of the Nvidia Shield connected to a UPS when power fails? I'd like to avoid dinging the Channels DVR Server I am setting up.
No idea. However, maybe there is a way to use the HDMI CEC to power down the Shield when power is lost? If I am not mistaken, you can set the Shield to automatically power down using HDMI CEC.
The shield does not power down, it only goes to sleep.
I have a Raspberry Pi connected to my new AmazonBasics UPS via USB. The Pi runs NUT and shuts down Home Assistant (formerly Hassio) once the battery is just about depleted. It would be great if Channels DVR exposed a API for at least orderly shutdown (if such a thing is even required?) because NUT could then signal to Channels to do so as needed. Oh, and this isn't entirely off topic since Channels DVR runs on a Shield 
BTW, with the following devices connected to the UPS:
- Shield
- 8TB USB drive
- Raspberry Pi
- Eero
- HDHomeRun Prime
- Spectrum Tuning Adapter
- Modem
- 8 port gigabit ethernet switch
NUT reports the battery will last around 145 minutes which is much more than I was ever expecting!