Is there a document from that talks about how ML development works with Apple products and what is needed to get started?
A good starting point is to check out an overview of Apple’s ML focused development tools here:
https://developer.apple.com/machine-learning/
There are also some past WWDC videos which show you an example journey from idea to implementation such as this talk: Creating Great Apps Using Core ML and ARKit.
I highly recommend checking out this session on Friday: Explore the machine learning development experience