The ability to move an app to SD card is fairly outdated, and is dependent on both the firmware having that option and the app developer allowing the app to be moved to SD. Remember that this option does not move the entire app to the card -- it only moves a portion of the app (often a small one) which is mostly data, and not the key executable part of the app.
The other way of having an app on the SD card would be to format the card as Internal Storage, which is again dependent on the firmware (some manufacturers don't allow this, and it was only possible starting with Marshmallow). In either case, having apps on the SD card is not advisable anyway, since SD cards are much less reliable and much slower than internal storage, which can lead to system instability and performance issues.
This thread might shed some light:
https://www.reddit.com/r/Huawei/comm...d_as_internal/
