"Google released the new Android flavor to its Pixel and Nexus hardware lines,"
Well kind of. For some of them. On some carriers. Not really.
"other device makers are set to push the upgrade out to their devices over the remainder of the year."
That's awful presumptuous. Only some have even mentioned upgrading phones, and those only phones which were just released (after the supposed general availability). I doubt ANY non Google phone will see Oreo before the end of the year.