There seems to be credible proof that a Halo game is on the way to PlayStation.

A Halo fan community called gruntdotapi specifically looks at data and tools to find out what’s up next for the Halo games. They made this claim on Twitter today:
I honestly didn’t expect to come across this today… But I can now OFFICIALLY CONFIRM:
A Halo game is coming (very soon) to #PlayStation. As of now, there’s no sign of a version for the #NintendoSwitch (2).
Digging… #API
They then clarified that the data appeared on the retail API, but has no ETA. It also shows a new ID so it doesn’t appear to be Halo: The Master Chief Collection.
As a quick technical note, API is an acronym for application programming interface. An API is not a program in itself. Instead, it’s a ruleset for how two different systems interact with each other. In the same way that there are different sets of rules between how judicial courts hold hearings in different countries, different APIs may have slight or drastic differences between each other even if they do essentially the same thing.
Dataminers have been looking at APIs to find out about games for some time now. SteamDB itself is based around accessing Steam’s API to retrieve data. So, there’s credibility to this claim that a Halo game appeared on PlayStation’s API.
We have seen in the past few months that Microsoft has managed the rollout and announcements of their own games making their way to the PlayStation 5. We have already seen Forza Horizon 5 get released on the platform, and Gears of War games get announced for the console.
There’s certainly some shock value to the idea of Halo, the game that put Xbox on the map, appear on the console that Xbox had to fight to establish itself, PlayStation. As Spencer has argued, this is the right thing to do to make sure that Microsoft’s developers find success for their games.
But then, there’s also a flip side to this that PlayStation fans may not care about, but Sony itself does. Microsoft is already dominating PlayStation 5 as one of the biggest publishers on the platform. Between Call of Duty: Black Ops 6, Doom: The Dark Ages, Diablo IV, the abovementioned Forza Horizon 5, and Indiana Jones and The Great Circle, Microsoft has kept releasing hit after hit.
Sony can talk about the royalties they get from Microsoft for publishing their games to PlayStation 5. But Microsoft’s domination hampers Sony’s ability to sell their own games on their own platform. In this strange way, Microsoft’s and Sony’s rivalry does continue, and with the smaller number of Sony titles for this year, they can’t afford to have any of these games undersell. Marathon itself may already be as good as cancelled, which is why we believe Sony will try to protect Ghost of Yōtei as much as they can.
If this Halo game, even if it turns out to be a smaller title, releases close to Ghost of Yōtei, it could materially affect Sucker Punch’s sales. Of course, the same would be true for other 3rd party games releasing on PlayStation 5 close by, such as Gearbox’s Borderlands 4 and Konami’s Silent Hill f.
On the other hand, all the wildest rumors of the ‘whole slate’ coming to PlayStation 5 didn’t really play out the way Xbox and PlayStation fans expected. If this Halo mention turns out to be the next big Halo Studios game, that title may not actually come up until the next generation of PlayStation and Xbox.