See, it turns out that the Rabbit R1 seems to run Android under the hood and the entire interface users interact with is powered by a single Android app. A tipster shared the Rabbit R1’s launcher APK with us, and with a bit of tinkering, we managed to install it on an Android phone, specifically a Pixel 6a.
Edit: Someone also got doom and Minecraft running on this thing
But it's android, so linux, so GPL2, so they have to share these modifications (if they really exist). It's bootleg until soneone sues them.
AOSP is not GPL
They wrote "lower level firmware modifications", AOSP runs on Linux kernel, and firmware modifications usually mean they modified the Linux kernel. This device seems like a regular Android phone, and afaik this rules apply to all Android phones, that's why Android rom cooking can exist.
This was a marketing post, not a technical one. Unless we see any git branches or ROM teardown we won't know what they were doing. I highly doubt that they did any kernel patches though.