Beta is available to a thousand selected testers. We do not know how long the closed tests will take. What we do know are the contents of EMUI 10. It is said to contain a series of security and performance updates as well as a few new functions, like the option to divide display into a few smaller, separate displays.
Devices eligible for the beta are the Mate 30, Mate 30 Pro, Mate 30 Pro 5G and RS Porsche Design smartphones. If that is not enough novelties for you then know that EMUI 10.1 will be officially revealed some time in March.