A Z80 port is currently under development in a branch:
The assembler and linker from the SDCC package are required:
The compiler produces ZX Spectrum tape files in the TZX file format. They are suitable for running in emulators. An open-source emulator that works is FBZX:
ROM images for the emulator are available here:
They are copyrighted and are not free (as in freedom), but are legally available for use in emulators (not in real hardware), and are also repackaged and redistributed in Linux repositories such as RPMFusion - nonfree.