> The product was soon re-branded to Aurora OS. Aurora OS is an independent, “standalone” product and derivative work of Sailfish OS, and property of Open Mobile Platform LLC.

From your link. Is there any evidence of them pushing code back upstream?

Yes, the latest release have seen some code contributions from Aurora. Some well-known people in the community even work for Aurora, like coderus.

To be fair, without the Russian investor, there would be no Jolla anymore :)