With small changes to @ssfrr's
https://github.com/ssfrr/nrfjprog.sh/blob/master/nrfjprog.sh I was
successfully able to manually flash a new firmware:

Capturing terminal outputs from connected devices also works.

This will be sent to AWS IoT MQTT topics.

The RPi now connects to AWS IoT to receive jobs, and it will flash the firmware
to the connected and collect the output of all terminals:
https://gist.github.com/coderbyheart/c717cbf57c5f7041a5e3c315bf30617d

I've started to add the necessary resources to the AWS version of Bifravst:
https://github.com/bifravst/aws/pull/375

The setup for AWS is done and I have the first CI runs on GitHub actions hitting
real hardware! No assertions, yet, but I already have the log output from the
device available. 🌩️

Next up is coming up with a way to describe assertions against the log output.