Yeah, the "put Linux on this" thing concerns me. In principle it's not that hard; in practice someone has to do the work. I don't want to be the guy that does the work :).
It boots a perfectly ordinary Linux-kernel, but with a non-standard initrd and init-sequence.
It's a Nexus so the bootloader will be open and unlockable, and you will have the source available for the kernel too.
That's not the same as having access to all the userland utils and a full, ready distro. No. But it's a pretty open end with almost no restrictions, completely unlike anything made by Apple so far.
Yan can boot the device with any kernel and initrd you like, you can transfer files to the devices and test your compiled arm64 binaries from a terminal. You will be met with zero technical restrictions or locked doors.
Hopefully somebody will do it soon.