I don’t think their intention is to compete with Home Assistant at all.
Based on the description and positioning of CUBE OS on GitHub, eWeLink CUBE is currently much more focused on a different problem space.
CUBE OS is mainly about locally onboarding Zigbee devices and eWeLink-supported Wi-Fi devices, and then bridging them locally via Matter into the platforms users already rely on — such as Apple Home, Google Home, and even Home Assistant itself. This is fundamentally different from Home Assistant’s philosophy, which aims to centralize everything into one single system.
I think their goal is not to act as a central hub system itself, but to help users easily onboard devices and bridge them to the hub platforms they already prefer — in a way that feels intuitive and requires little to no learning curve.