The short answer to both of those questions is that Sea of Thieves is not on PS4, nor will it likely ever come to PlayStation 4 or PS5. That’s because Xbox Game Studios owns Rare, and the likelihood of an Xbox Game Studios title ever being released on a Sony platform is almost nonexistent.
As reported by GamesIndustry.biz in 2019, Microsoft has previously allowed games that were initially released on PC and Xbox consoles to later appear on other consoles to honor “existing commitments,” they “have no plans to further expand [their] exclusive first-party games to other consoles.”
Since then, Microsoft has stuck to that in an effort, no doubt, to bolster its first-party lineup, which has been criticized as lacking for some time. Titles such as the upcoming Starfield, which is in development at Xbox Game Studios subsidiary Bethesda, will be a PC and Xbox console exclusive when it launches in late 2022.
Microsoft’s tactic isn’t surprising in the slightest, considering that very few Sony exclusives have released on PC. The PC port for Bend Studio’s Days Gone released earlier this year, and the PC port for Guerrilla Games’ Horizon Zero Dawn release on August 7, 2020.
It’s highly unlikely they’ll ever release on an Xbox console.
So right now, you can’t play Sea of Thieves on PS4 or PS5. The only way to play Sea of Thieves is to play it on PC, Xbox One, or Xbox Series X|S. The game retails for $39.99 but is included in Xbox Game Pass for console and PC at no extra charge. Game Pass Ultimate is $14.99 per month, while the standard version of Game Pass is $9.99 per month.