According to the ASOP documentation, it is no longer possible to use FDE and the user is forced to use File-Based Encryption
Note: Devices running Android 7.0–9 support full-disk encryption. New devices running Android 10 and higher must use file-based encryption.
Though I understand the argument for convenience (morning alarms, updates, etc), there are several strong use-cases where it's better to have a FDE with a very long passphrase -- consider journalists, activists, political prisoners, etc crossing borders with oppressive governments. It's better to just turn the device off and rely on FDE to protect absolutely everything in these situations.
I see that GraphoneOS's FAQ page talks about FDE and also Android 10, but doesn't directly answer this question.
Do the GraphoneOS releases that are based on Android 10 still use FDE? If so, how?