Note Google release a "pure" version of Android and that is what they put on their own (Google) phones and tablets.
Other companies like Samsung etc take that "pure" Android and then add function to it and extra apps and so on, and then release it for their own phones and tablets.
However as a particular phone or tablet gets older then companies don't bother to ship an updated version of Android for older devices (due to the extra work involved).
So my guess is Huawei have not bothered to do this.
You can go in to the Android options and "check for system updates" or words to that affect, but it may say that no update is available.
I believe some "hackers" can do this sort of thing, and download and update Android and put it on their phone or tablet, but the danger is some of the features on the phone or tablet may stop working so it is risky.