If you register as a developer with Google you can gain access to early, usually quite unstable versions of the next Android version to test your apps and build the, to be compatible. It also allows you to feedback to the Android team to help them iron out and bugs found while using the build.
The dev betas come before a more stable public beta that anyone with a Pixel – and increasingly other supported devices – can install at their own risk. This may be the first year where the original 2016 Pixel does not get support for the beta. Google outdid itself by offering Android 10 on the device as it was only promised up to Android 9.
The appearance of this page does not tell us much apart from the fact the dev beta of Android 11 isn’t far off, and that someone at Android HQ is a little trigger happy. But it’s a reminder that we’ll not see a sweet treat name for Android again, and 11 will be the second version to be simply numerical.