Thanks for the quick response!
I'm using the same Universal Render Pipeline asset for all Quality levels in my Project Settings, so I assume that means all levels will use the same MSAA value as set in the pipeline asset. I also tried editing my ProjectSettings/QualitySettings.asset file in a plaintext editor so that all the "antiAliasing: x" serialized properties have the same value, but it looks like Unity is changing those settings back without me doing anything (specifically, the "Very Low" Quality level is always reset to antiAliasing: 0).
I do have "Initialize XR on Startup" in my XR Plugin Management settings for Android unchecked; I added those extra waits you suggested to my manual XR plugin initialization coroutine but that didn't seem to change anything. No MSAA works fine on the Focus 3; enabling any amount of MSAA works in the Unity Editor but crashes on the device.
I'll work on reproducing this issue in a minimal project, but I probably won't be able to get to that until next week.
Thanks again.