As most of these doors are located in the balcony area, one would not be able to spot them at the street level. If you think the windows are rare, these doors are even rarer.
These relic may require some work to restore them to the former glory. The handles seemed broken too.
Too bad the green panes were replaced. Otherwise, it would have been a complete set.
The other things the owners will not keep is this:
I think there is only so much one would do when it comes to living in a conserved flat. The occupants needed to make it functional. The chimney system does get in the way as it has been placed in a rather awkward position in the kitchen.