I think the docs are light because the primary goal for them is not to provide everyone with a well documented linux on esp-32-s31 guide, but rather this that they shared:
"I'm currently working on a hackable music player and I used to prototype with the OG esp32, and tbh if I wasn't for Bluetooth audio I'd move on to S3 already" ( from the links in this comment https://news.ycombinator.com/item?id=49134987 )