How much of this is in Wine? i.e. how far off is Wine for Android?

And I guess this only works on x86/x64 Android devices - not ARM?

Yes, only x86.

Codweavers Crossover is a more supported version of wine. It is essentially wine at its core, but it adds some extensions for ease of use.

How did that happen historically? In the blog post they make it sound as if they invented and built the whole concept, while you make it sound like they packaged up some open source software.

Wine predates crossover by a few years. The company behind crossover is CodeWeavers (https://en.wikipedia.org/wiki/CodeWeavers), founded and run by mostly the same Wine core developers.

Crossover is a paid-for version of Wine with more patches/hackwork which may be less acceptable in the wine mainline (think of it somewhat like wine-staging: https://www.wine-staging.com/), as well as commercial support.

I really like their model. It allows Wine to thrive as a foss project and gets the project funded.

It's a model that's common on youtube: you can get the content for free, but if you pay, you get it before everybody else.

Does this mean that potentially most Windows apps can run in a Chromebook one day?

All I care about is if will run Cygwin. <ducks>