I have got a Raspi2, so I wrote https://github.com/home-assistant/operating-system/releases/download/13.1/haos_rpi2-13.1.img.xz to an SDcard … and “Preparing Home Assistant” is now taking a few hours.
Hopefully a nice result tomorrow morning … fingers crossed …
EDIT: already there! Not bad for a raspi 2 (from 2015) … 2-3 hours.