Sorry, we don't have further information about the further upgrade plan for ZB601KL.
The latest Android 10 beta version for Zenfone Max Pro M1 can be downloaded on ASUS official support website.
ASUS will continuous provide regular update on Android 10 beta version: https://www.asus.com/supportonly/ZenFone%20Max%20Pro(M1)(ZB601KL)/HelpDesk_BIOS/
If you have any recommendations or face any issue, please provide your feedback on Asus forum (Link: https://zentalk.asus.com/en/categories/zenfone-max-pro-series-a10_en).
Please read the terms and conditions associated with the beta version before updating your Max Pro series model.
We apologize for any inconvenience caused. For further updated information related to updates, please stay tuned with our social media channels or visit our Asus support website.
Thank you for your continued support and patronage.