The Project Fi Moto X4 got its promised Android 8.1 Oreo update more than a month ago, but the retail and Amazon Prime variants were skipped from the initial roll-out. Well, that's not the case any longer since Motorola has started to push out the same update tot he Amazon Prime and retail Moto X4 units.
And when we say the same update it really means that it's the same version that the Project Fi Moto X4 received in early May. Apparently, Motorola didn't have the time or didn't want to include a newer security patch in the update, so the one for the month of May will have to do.
Still, since the Moto X4 went on sale with Android 8.0 Oreo on board, this isn't such a massive upgrade, so don't expect any major new features or improvements.
Just like the retail variant, the Amazon Prime Moto X4 model comes unlocked and it's about $20 cheaper, but packs quite a lot of bloatware, so it might not worth the trouble if you hate having ads on your phone's screen.