I did a google search but couldn't find the answer . I would try to contact Huawei customer support and they might be able to answer your question
It was just as unclear when the regular Mate 9 came out. I contacted Huawei about it when I got my Mate 9 and their response was to use the "vault" on the phone. They basically implied the whole phone was not encrypted.
I was hoping someone that has one could check.