For a western world targeted app, the stats are around 35-40% for Oreo right now. So you seem to be deliberately ignoring your own installation stats just to complain - the dashboard you're posted is pretty much not relevant for anyone but multi-million installation apps like Facebook. In other words, if you ignore Oreo users, you're ignoring more (wealthy) people than there are owners of iPhone X.
Also I simply fail to see how releases are dividing the market, considering the fact that for most apps new releases don't really require nearly as much maintenance as they do for new iOS releses. Granted, Oreo and P require a bit of work for apps that run in the background, but vast majority of the apps will just work if they implemented proper privacy respecting permissions since the release of 6.0 in 2015.
Just to be clear - I don't mind if you give up Android development (good riddance actually, way too much toxic people in the community), but PLEASE do not spread misinformation.