It was enough time for the group to travel up to the Diamond in Texas, as well as enough time for Morgan to make his way down south after the All Out War’s conclusion.
The second thing Ian Goldberg mentioned to TVLine is that Daniel is alive and “out there,” which also isn’t necessarily the most straightforward word choice.
Ipso facto, it is clearly enough time for a family-less Daniel to make his own cross-country trip up north to the land of Alexandria and Hilltop, especially since The Walking Dead is making its own big time jump going into Season 9.
We know that well over a year, and possibly even more than two years, passed between the dam’s destruction in Mexico and the group’s current exploits with Maggie Grace’s Al.