Phoenix Point is currently exclusive to the Epic Games store since it's launch back on the 3rd of December, but community backlash over the exclusivity lead to the announcement that it would also be making it's way to the Microsoft Store and Xbox Game Pass. Sadly it seems that the release for the Redmond platforms has been delayed.
The game is currently still missing from the Microsoft platform. The game's developers, Snapshot Games, did state that they were aiming to release the game on both platforms the same day, but as of yet, it has yet to appear. It seems the explination, as muted on Reddit by one of the game's community managers, is the game is awaiting Microsoft certification.
In an announcement on the official forums, Snapshot Games apologised, stating;
We were exceedingly busy getting the game itself ready, and being inexperienced with Game Pass and the Microsoft Store, we simply had not properly prepared the groundwork to get the game released on time on these platforms. Compared to other platforms we’re on these platforms require a number of prerequisites, from Microsoft certification to legal documentation review. While these are now mostly complete, they have given rise to a number of new delays.
In more bad news for those looking forward to the Microsoft release, it seems that not all content will be available either, as certain content has to stay exclusive to the Epic Games Store, which is also delaying the release.
As a result, there's no release window for the game now, and the game remains effectively an Epic exclusive until these legal and contractual obligations are sorted out.