no adaptive icon, the widgets don't work, and the supposed app shortcuts aren't available. The current icon sticks the old Wikipedia app icon (a square) into the space of a circle. Both app widgets simply display "Problem loading widget" when placed on the home screen. When long-pressing the app icons, none appear.
Wikipedia app version 2.6.206-r-2017-10-30
on Android 8.1 DP1
Link to OTRS: https://ticket.wikimedia.org/otrs/index.pl?Action=AgentTicketZoom;TicketID=10457352
It's not really feasible for us to guarantee the app to work on Developer Preview versions of Android. The app works correctly on 8.0 (API 26), which is the current production version of Oreo (with the exception of adaptive icons, which is captured in T174301). The app also works correctly in an emulator running API 27, so I'm not able to reproduce any of this behavior. There's no telling what kinds of quirks or inconsistencies are present in the Developer Preview, and we don't have the resources to account for all of them.