At this stage it looks similar to the Espressif-authored esp_iot_rtos_sdk, but with some significant changes under the hood:
- Revamped build system
- Source elements reworked to make them as compatible as possible with upstream components for easier updating & upstreaming.
- Using a vanilla BSD license so it's easy to incorporate into both open source and commercial projects.
Goal is to provide fully open source code above the MAC layer. There are some components still remaining to reach this (outlined on the issues list), but you can build working projects with it now.
It's still early days, but work is in progress and contributors are welcome.