It's all kinda sketchy with Espressif. They do not hesitate to ship hardware prior to publishing comprehensive documentation. The complete P4 TRM documentation for the PIE extension didn't arrive until June 2026, although it's been possible to buy P4 dev boards for roughly two years.

They also don't hesitate to signal "mass production" availability while they're still working out substantial errata. Espressif will ship the moral equivalent of "engineering sample" silicon (no, they don't call it that) for early use by their supported customers, and eventually iron out the bulk of the issues in later silicon.

Espressif applies the "release early, release often" model of open-source software, but for silicon, and I love them for it. But it does create pitfalls for early adopters that don't understand the game.

So the big hole in ESP32-S31 SIMD documentation (literally "Coming soon"[1]) isn't surprising, despite the fact that you can buy official and third party dev boards right now.

[1] https://esp32-s31.espressif.com/en/docs/9-Technical%20Refere...