According to Joe Neate, the game's producer, throughout the port's development, Sony helped the team a lot, holding meetings with Rare staff and even providing their own employees whenever they needed them.
Even when the project was still a secret, Sony was already working closely with Rare to make it possible. "If we went to visit their studios, we had to go without wearing a Sea of Thieves T-shirt, as you can imagine why," commented the producer.
“This is the first time in Rare’s 40-year history that we’re developing on a Sony platform, which is incredible. It was quite surreal for us, getting on a call and being presented with a set of slides about a platform that we never thought we would get an opportunity to go ship on. But honestly, for our tech team, it was like: ‘Let’s just get kits in and start experimenting and figuring this out.’ We had them hidden away in a secret part of the studio with frosted windows and no one could peek in. It was excitement as much as anything else.”
via TheGuardian