Yes. Android is sufficiently different from a stock Linux distro that it absolutely counts as a unique operating system. ChromeOS is also unique in interesting ways, although less successful. It's certainly a production quality OS.
Perhaps more importantly, both of those are complete and have real users who found value in them.
> ChromeOS is also unique in interesting ways, although less successful.
Chrome OS absolutely dominates the education market. So less successful than Android, sure (but so is literally every other OS at this point), but still very successful.
That's just not true. It might not be seen in your particular country, but it's definitely not US centric. Canada, Sweden, and New Zealand are also countries where Chromebooks are sweeping education https://www.neowin.net/news/chromebooks-are-seeing-huge-adop...
And the reasons why are pretty straightforward. Kids can't really mess them up, they are highly sharable (eg laptop carts), they are cheap (generally), and they have centralized management for schools that's otherwise typically limited to enterprise markets.
