Finally it also works on the Raspberry Pi Zero 2! Here is an image of the running system; I'm using the original Raspberry Pi monitor and a Lenovo ThinkPad TrackPoint keyboard which has three mouse buttons (as suggested for the Oberon system).

I attached a ready image (oberon-rpi3.img) which you can flash onto an SD card if you want to run the system on your Raspi yourself. To do so, unpack the image; on Linux, run this command to flash the SD card: sudo dd if=oberon-rpi3.img of=/dev/sdX bs=4M conv=fsync status=progress && sync; on Windows or Mac you can use the Raspberry Pi Imager or e.g. Etcher.

Of course you can also build the whole system yourself, and even the toolchain if you want. See this release for the required Raspberry Pi bootfiles and a pre-compiled toolchain for Linux x64. The Linux build script is in the arm32/build subdirectory, also a script to flash the SD card. If you just need an image to run the system on QEMU, see this release.

I tested the system on both the Pi Zero 2 and 3b. User reports confirm that the system also works on Pi 2b version 1.1. The Pi Zero 2 is a very good fit for the Oberon System; it is small, available for less than 20 USD and will be in production until at least 2030.