Yes ,you saw it right Gorr is connected to Venom as Gorr became god killer because of the necrosword which was made up entirely by symbiote. Here below is the full origin story , how he became marvel comic’s one of the most deadly god killer .
3000 years ago , there was a planet without name . It was drowned by hunger, sadness, death . Gorr was the leader of clan , all of them prayed to god but there nothing good happening to them . After a tragedy he lost his wife and all of his sons due to starvation .
That moment everything changed Gorr lost faith against god , he gave up hope and expressed his belief that there were no gods . But clan members were too superstitious he was exiled by them , leaving him with nothing in the desert like condition . he was crawling on sand hopeless wanting to die . That moment he saw two gods fighting in sky , eventually they crashed on ground . Gorr saw that one god was wearing gold armored suit and other god was dark elder god Knull ( creator of symbiotes ) , Knull was unconscious and other god was pleading for help from Gorr .
Gorr got more angry and said to god that why no one came to help when we were praying to you , we were straving , dying but no god came . the necrosword sensed the hatred, anger , rage of Gorr . So the sword get bonded with him and hence he killed the dying god with the sword . Then vowed to seek revenge and set out to kill all existing gods . That’s why he is called Gorr the god butcher . He is one of the strongest villain of Thor in Marvel comics .