https://www.escapefromtarkov.com/preorder-page#preorder_unheard_edition
Edge of Darkness owners do not get it for free, despite earlier claims on EOD sales page stating all upcomming DLCs and expansions are free with EoD.
Edit: The official Discord is of the rails with spam.
It was already DRM-free on Steam, but it’s always great to see a GOG release.