Just letting you know that the latest pitool does work on the Pimax 4k.
That version is currently 18.104.22.168 using firmware 22.214.171.1245
no issues with installation however, after installation you need to change the language to english if that is your preferred language. before you use it. With this version you gain the added features of contrast per eye and brightness per eye.
Note that smart smoothing does not appear to work with the 4k.