Hinterland

Hinterland is the Hunter ritual armor set, the Hunter counterpart of the Biosphere Explorer Titan set. Its pieces, including the Hinterland Cowl, are earned from ritual activities.

The Destiny 2 wiki lists the cowl as a Season 24 item whose vendor is Xûr. Other reports place the ritual sets in Season of the Witch (2023), with pieces dropping from Vanguard Operations, Crucible and Gambit. Check the in-game acquisition for the current source.