Thank you for your answer. Yes, I am already in the process to disentangle the Photos Library from the the TC, but was hopeful that I can open it one more time to cleanly export all of my pictures in their folder structure, instead of doing a general dump of all pics in the "Originals" folder to another drive location. Originals is not human readable of course and thus it will be quite a task to sort my pictures into a meaningful order again - without the help of the Photos Export function.
Does anyone know if I need to grab also all of the pics and home videos of the "Masters" folder? Or will I have grabbed everything if I restrict myself to the "Originals" folder? And then there is the "Modified" folder which might have better looking versions of the originals - since supposedly that was the reason to modify them in the first place. But heck, I guess I'll just have to do that again. It is 40.000 pics though.
The SSD looks neat and small - a good solution if one stays with the Photos Library.
I tried to look for how the TC is formatted, but couldn't figure out where to find that info - it is not in Cmd + I (Info).
In the manwhile I have also tried the way via a partition on my laptop (a 2nd volume) with the previous MacOS High Sierra, but got the error message that the Photos App, i.e., OSX, is too old to open the library file. I expected as much, but now I have tried that , too. I suspect that Monterey must have bent my library structure out of shape in trying to open it the first time from the TC, left it's "scent marks" in there, and thus nothing older than Monterey can open it anymore.
If this is so, then I have lost my love for Photos and will move toward s.th. else, unfortunately. Probably Synology Photos with a 100% human readable photos filing structure - that even newbies like me can understand and safely manage and back up.
