All 3 billion Android devices in the world. It's pretty crazy when you think about it. Also 96% of the top 1 million web servers and all of the 500 fastest super computers (excluding quantum) in the world.
Eventually, if things keep progressing, they'll be able to do certain things like factoring primes faster than conventional computers. But, the clock rate will probably always be abysmal.
Remarkable eink tablets. Buried deep in the settings they actually give you the root password so you can SSH in. Also, it comes with an epic .vimrc file.
But, the software they ship is completely closed source and displaying anything on the screen requires hacking the binary (each software release). They have have been the opposite of helpful to open source for the last few years and have stooped to a cloud company trying to collect your data.
https://github.com/reMarkable/linux
At that, there are ways to hack it of course (Fairly certain it “ruins” some returns/warranty policies, but if you can in those cases, you can easily revert the modified bits if needed)
Kindles too. You can jailbreak them and get a shell. They're so much more useful when they're jailbroken. They can read multiple other formats, they can get books from a fileserver on your local network, the jailbroken reader app is better, etc.
Yeah, it used to be just web servers in a data center. Bigger systems used mainframes. Consumer electronics used custom RTOSes or other custom boards. Now it's everywhere. It's used in the biggest systems, like the computers that power virtually every Google product, and the smallest systems. It's almost not worth it not to use Linux when building a tiny device because it makes the dev cycle so much shorter.
Passenger information systems in public transport. Some might run some kind of embedded windows, but most run on Linux. Certainly here in Czechia, but I believe it's common at east throughout the Central Europe.
I was product manager at a company that made PTZ cameras based on Linux. The company was acquired a few times but still actually manufactures them in Minnetonka MN. Kind of fun working at a place the had development, manufacturing, support and engineering in one building.
Well, it turns out only a handful of companies actually make image modules. I would say it is better in terms of US based support, firmware, hardware design, and the fact it meets TAA and buy America compliance. I've seen these cameras in the DoD and even in the oval office. If you want a camera that is absolutely not spying on you I can vouch for these because I have watched the firmware get built on these.