There is a lot of cosplay of Chinese copyrights, e.g. Genshin Impact, Azur Lane, Arknights, Super Cube [1] as well as mobile games for which I've collected 20+ photo sets that don't seem to have any documentation in the west. South Korean titles like Blue Archive are big.
This is a Google-internal only GA. JJ is available externally just fine. Google is mainly a linux-dev shop, with all other platforms being second-class citizens.
Furthermore, many engineers at Google work on Macs, some even on Windows, but the actual code runs on a Linux box in a datacenter. I use a Mac, my editor is local, my terminal is local, but it's all SSH/remote to the linux box, so I've never needed jj to run on my Mac. This, or a high powered Linux desktop, are the norm.
The main exceptions to this are devs who work on iOS or macOS software, who will sometimes do local builds on their physical machine. They would benefit from jj support, but there are more hoops to jump through, and the jj port will most likely be less about running on macOS and more about jj supporting the weird ways in which source is accessed.
The datacenter OS doesn't have to be the same as the developer OS. At my work (of similar scale) the datacenters all run Linux but very nearly all developers are on MacOS
MacOSX is a popular choice for dev boxes (if I understand correctly, they provide some pretty good tooling for managing a fleet of machines; more expensive hardware than a Linux dev machine fleet, but less DIY for company-wide administration).
... but Google solves the "A Linux fleet requires investment to maintain" problem by investing. They maintain their own in-house distro.
Not really, it is just a well known outside distro plus internal CI servers to make sure that newly updated packages don't break things. Also some internal tools, of course.
Relative to what the rest of the world does, that is maintaining your own in-house distro.
It's downstream of Ubuntu (unless that's changed) but it's tweaked in the ways you've noted (trying to remember if they also maintain their own package mirrors or if they trust apt to fetch from public repositories; that's a detail I no longer recall).
