When talking about Mediapipe and ARKit shape keys with a friend I shared this link from 20241126182208. After seeing that, they recommended the following resource:
https://pooyadeperson.com/the-ultimate-guide-to-creating-arkits-52-facial-blendshapes/

I remember seeing this before and liking a lot better, but i forgot to take a note of it.

We also had a conversation about what the Mediapipe shape keys were, and I had thought that they were slightly different. However, upon reading the note I'm reminded that I had some reason to believe that the Mediapipe and ARKit shape keys are the same. I think I wrote it after having a conversation with the developer for SnekStudio about it.