There was fiber deployment in the GDR and plans to extend it already before the OPAL project, which came after reunification. I remember our East German CS network professor talking about it with passion but fail to find information online. Which doesn’t surprise me, since history is written by the winners. I trust his personal stories more than the lack of information online.

It could be. Even much stuff from the 'winners' from before common internet access is lost ;->

OTOH, considering how well the 'megabit-chip' went, I'm wondering wtf they'd do with fiber, at the times? For the military, agencies, ministries and some universities maybe, but for the masses? How common was the 'stinknormales telephon' in households, back then?