Birdy are equipped with external bearings !

I am curious to know if R&M adapted the chainline for the Rohloff Birdy compared to the Nexus 8 Birdy.

Replacing your Nexus 8 Birdy by a Rohloff Birdy is of course a radical solution and change, the Rohloff hub is a completely different category of hub than a Nexus 8 !