Then that would be a starting point to compare behaviour.
Note that all the stuff about needing the right package to contain the keys so that you can play a commercial DVD is correct but before you even get to that point, the device has to be recognised.
From that perspective and with a goal of fault isolation, I would try a data DVD first. You could also try a commercial audio CD and a data CD before that even.
Also I do wonder whether the Librem 5 has the battery capacity to power itself and a DVD player for very long. I would probably use a dock with external power if this is a configuration that you plan to use much.
Hereās what tricks detected after being plugged into the dock with external power (since the beginning of the conversation, Iām always plugged into the dock when I plug into the CD drive) and with a CD (and not a DVD this time. But I donāt have CD or DVD dataā¦Yesterday Iāve tried with a CD-Rom and it does not work) in the drive that I canāt find when I do ls -l /dev without being plugged into the dock with the drive :