According to Corellium’s Chief Technology Office Chris Wade, this is a full version of the Ubuntu desktop operating system that has been booted from a USB drive. While Wade does not dive into the details, he does claim that the version of Linux they installed is “completely usable” on Apple Silicon computers.
https://twitter.com/cmwdotme/status/1351838924621099008
It should be noted that this was possible as the version of Ubuntu was the one that’s meant for the ARM-based Raspberry Pi, and since the M1 chipset is based on ARM, it would make sense that it has some level of compatibility. However, it appears that this port isn’t without its limitations.
For example, it appears the GPU acceleration has been disabled and set to software rendering mode, meaning that its graphical performance will be slower. However, it is still an impressive feat anyway and if you are interested, Corellium will be posting a tutorial on its Github account on Friday.