With the help of Mech-maniac in my last thread (https://www.reddit.com/r/datarecovery/comments/oq0fuj/seagate_barracuda_spinning_up_not_detected/) the drive is now being detected and I can see the partitions:

diskutil list

ddrescue does not manage do successfully read anything off if (although it does not report errors either). photorec hangs when selecting the device.

The hard drive spins up and then makes this sound:

Hard drive trying to read?

When trying (and unfortunately not succeeding) to update the firmware on a Windows computer, one of the partitions could be listed with the following content, although the folders had odd permissions and were inaccessible:

Weird content on one of the partitions.

Thoughts on what could be up and down in this would be greatly appreciated.