The HAL is Linux in this case, but you might need to send pull requests to enable additional drivers, depending on the hardware.
The currently supported platforms are the Raspberry Pi 3 B, Raspberry Pi 3 B+, the PC Engines apu2c4, and qemu x86-64 (I’ll update gokrazy.org with an overview about this in a minute). As long as your hardware is similar enough to one of these, chances are things just work.