In Android 6 (the version of Android that is installed on the device this thread is about) SD cards with high enough speeds can be adopted onto the system storage and the combined size appears as a single block of internal storage to apps, they don't know they're running off an SD Card.
I'm iffy about that adoption system, as it also makes the cards useless as removable/swappable storage.
This because the adoption process formats and encrypts the card, thus anything stored on it can only be accessed from within the device that adopted it.
