Still having some issues with this.
I fired another email off to Jolla and according to them my device should download an update that unlocks the commercial support, but despite checking for updates there's nothing found.

Jolla say that the Android Support is already included in the free download but is hidden until it is unlocked with the license key for the full download. It's supposed to happen when you've logged into your Jolla account with your device. Once your IMEI is matched with the account it triggers an OS update that then unlocks the Android support. But for some reason this is not happening with my Xperia 10 II.

I originally purchased Sailfish X on my PC with a view to flashing it to an Xperia X but never got round to doing so, so the license wasn't used so Jolla transferred it to the Xperia 10 II. So I think it's the IMEI that's the hurdle.