I've been looking at the Monitor One to outfit a large number of vehicles. I'm wondering if it's capable of enabling a local user interface for when connectivity is interrupted allowing user interaction with the system. Would I need to have an additional higher power (Linux?) device to make this happen?
It depends on the size and capabilities of the interface you want to use. If you want a large touchscreen like you'd have in a modern vehicle, that's beyond the capabilities of the Monitor One/Tracker One (nRF52840).
If you use a smart display, like the ones from 4DSystems, which use serial to communicate with the MCU, but do the touch processing and rendering on the display itself, work fine.
The middle ground is where things get tricky. In order to have a reasonable refresh rate, most non-smart displays will need an SPI interface, but that will be tricky to get out of the Monitor One and does not like to work over long wires. The speed and RAM limitations on the nRF52 will also come into play. It won't be easy and you may need to temper your expectations if you go for a non-smart display.
Thank you Rick. Super helpful