No, that is not an Apple Macintosh connector of any generation.
I have not seen that keyboard before either. Could be for a special application.
The fact that it has separate Return and Line Feed keys makes me suspect that it could be an ASCII keyboard, I.e. that the connector generates some kind of ASCII codes in parallel. I say "some kind" because the ASCII code would have had to be a special variation with German symbols in that case.
ASCII keyboards were off-the-shelf parts used for many different special devices.
