Google has a history of acknowledging the existence of consumers on Linux, and has published Linux binaries for various closed source products in the past. I am writing this comment to you at this moment using one such piece of software.
Does Apple have a history of publishing applications built for non-Apple BSDs?
Well, Apple gave us CUPS. Plus, recently they announced Swift will be supported on Linux, too. Now I'd be really happy if they also ported iTunes to Linux (I'm currently forced to run the Windows version in VirtualBox) - or at least make their iOS devices more Linux-friendly. IMHO there is hope.
CUPS was first released in 1999 and was adopted by most Linux distros soon after. Apple first adopted CUPS in 2003. It wasn't until 2007 before they bought the rights to the source code, hired the main developer and took over the development.
When companies build on open source, they generally don't make it easy for you to use the base product without their extensions.
So for all intents and purposes in terms of a platform, OSX != BSD and ChromeOS != Linux.