Asus has now joined the list of OEMs to send out an Android 10 build to their smartphones. The Taiwanese OEM is currently rolling out the Android 10-based ZenUI 6 beta build to users of last year's flagship, the Zenfone 5Z. The Zenfone 6's rollout is expected to follow soon.
https://www.notebookcheck.net/The-Asus-Zenfone-5Z-is-now-receiving-the-Android-10-beta.440257.0.html