Boox just announced that a
Beta version for Firmware 4.0 is available for the Tab Ultra C Pro.
Not sure if I am brave enough to install the beta, as I use my TUCP for work.
Also, I have no experience with Boox betas yet, so I am not 100% sure how the transition to the final version is going with Boox (just install the final version, no data loss, ... ???)