I doubt that at this point they do anything other than basic testing to make sure it at least boots on their Jolla-branded devices. There is no updated kernel, no updated Android compatibility layer, no updated Bluetooth middleware, etc. They introduced a bug on the Jolla Tablet something like three years ago where you can't take any screenshots anymore and it was never fixed, which means that either it's an easy fix which hasn't been implemented because they aren't spending any time to support it, or it's a difficult fix which cannot be implemented without causing numerous other bugs on other devices, which would then also need to be fixed, so they haven't implemented it because they don't go out of their way to support their older products. Either way, the point is, their focus is clearly on the XA2 and future devices.