https://developers.meta.com/horizon/documentation/unity/audio-ovrlipsync-viseme-reference/#reference-images

The above page is subject to removal, but the reference may still be useful. If the page disappears, refer to the PDF version of the page.

Viseme Reference _ Meta Horizon OS Developers.pdf

https://github.com/Ximmer-VR/Warudo-OVRLipSync

<aside> ❗ UNTESTED: I haven’t tried this yet so I’m basically talking out of my ass here.

</aside>

OVR Lip Sync appears to be a system made by Oculus that might be better at handling Lip Sync than ULipSync, which is the package Warudo uses to support Lip Sync. The page at the top contains a reference for example Visemes and their related Phonemes. To fully utilize OVR, you can create these expressions as Blendshapes on your model.
OVR support for Warudo is through an unofficial plugin available on Github, but you can technically just use the shapes defined on the reference page using Warudo’s default Lip Sync node. The OVR Node provides additional settings to the original node, which may create better results.