Chromacast dongle 2 with a nokia 6.1 does work. Casting is all done via the Google Home app. Even the Screen mirroring works.
On the Chromacast 1 Dongle it all works except for the Mirroring, it seems.
Im using the Chromecast 2 with Nokia 6.1 1 Sept. 2018 update and latest google updates on the phone. No issues with casting.
The only issue i see is that you cannot mirror your screen directly from the Cast button from the systems bars. But via the Google Home app mirror this works.
Im writing the above because I see NO confirmation that this works..anywhere.. I only see and find messages that it doesnt work.. Not even on the Nokia Support pages.