Late last year I bought a Nokia 6.1, which is part of the Android 1 program. I was attracted to this program by the notion that the OS on these phones was supplied and maintained directly by Google rather than the manufacturer. I have now found out that this is not the case, and the impact of this is that OS updates (both security and maintenance) come via the manufacturer, not direct from Google.
With Android 1, the handset manufacturer supplies and maintains Android as Google supplies it. Other phones contain a version of Android that is supplied by Google originally but may have been modified or added to by the manufacturer.
Buying an Android 1 phone therefore provides no better OS support levels, it simply guarantees manufacturer modifications and/or additions are not present.
My 6.1 handset came with Android 8, which was upgraded to 9 automatically within weeks. I had been receiving security patches up to April 2019. Since then no further security patches have come through, and this is because Nokia are not releasing them for this device yet. Not what I hoped I had bought into.