I feel kind of lost after obtaining Astrape power artifact and gaining access code to unblock tram from Santorini. I don't know how to unlock / unblock the Talos-Astrape tunnel, I don't know how to unlock Strabo / Pneuma, and I don't even know where to look. Observing highlands from the tram is supposed to unlock something, but I still have no idea what it unlocks.
Hoping for a walkthrough / guide, if available.