The release wave 1 only goes as far as September 2023, and it might be that Microsoft plans to go GA with datamarts before that but didn't publish it in the release wave, which I understand to be indicative and subject to change anyway:
https://learn.microsoft.com/en-us/power-platform/release-plan/2023wave1/
In this page they state: "These release plans describe functionality that may not have been released yet. Delivery timelines and projected functionality may change or may not ship."
In other words we don't know and can't rule out nor assume a 2023 GA date.
