"Android One phones will receive at least two years of OS upgrades," according to Google.

I interpret this statement as follows.

An Android One phone will receive at least two major version upgrades for Android within two years of the device's launch date. For example, an Android One device that launched with Android 8.0 will eventually receive upgrades for versions 9.0 and 10.0.

Is this interpretation correct? Am I missing details?

To clarify, Android 8.0 was a major release; Android 8.1 was a minor maintenance release.