We omitted the details for the sake of brevity (the article is already really long), but we run agents on the test devices and plug them into CI. Agents allow remote access for servicing remotely, and that's enough most of the time.
For things like system updates and taking care of the hardware - we do it manually today. The fleet is still small, so it is manageable but in the future we would like to consider a vendor, if we can find one.