One of the "under the radar" demos at Unreal Fest 2024 was the new ability to use nothing more than an audio dialog file to animate Metahuman lip sync animation. This video shows a Pre-Release walkthrough of how to use this functionality using the 5.5 Metahuman Plugin.
This video was recorded using the initial Pre-Prelease version of UE5.5, so there are still a few things to be ironed out, and it is possible that the functionality in the final release will be a little different, but this tool is quite effective and worth experimenting with if you have the chance.