ANOM was a black market cellphone platform sold to crooks with the promise of secret comms. Sadly for them, the software was made by the FBI, leading to many arrests. Since the chips were called in, the spooked Google Pixel 4s have been appearing online for sale and Vice bought one. Joseph Cox:
When booting up the phone, it displays a logo for an operating system called "ArcaneOS." Very little information is publicly available on ArcaneOS. It's this detail that has helped lead several people who have ended up with Anom phones to realize something was unusual about their device. Most posts online discussing the operating system appear to be written by people who have recently inadvertently bought an Anom device, and found it doesn't work like an ordinary phone. After the FBI announced the Anom operation, some Anom users have scrambled to get rid of their device, including selling it to unsuspecting people online. The person Motherboard obtained the phone from was in Australia, where authorities initially spread the Anom devices as a pilot before expanding into other countries. They said they contacted the Australian Federal Police (AFP) in case the phone or the person who sold it was of interest to them; when the AFP didn't follow up, the person agreed to sell the phone to Motherboard for the same price they paid. They said they originally bought it from a site similar to Craigslist.
A very thorough description follows. The tl;dr: stolen burners only, gentlemen, please!