Boot issues on Raspberry Pi Zero W

I’m trying to get RISC OS to work on the Pi Zero W with the Composite output. I used Raspberry Pi Imager to get the OS on my SD Card.

Right now, all I get is a black screen with a blinking “_” cursor. Pressing “Esc” on the keyboard brings up the “loading” screen above some tiny terminal text (mostly unreadable). Out of curiosity, I tried Removing and reinserting the SD card, which makes the “loading” animation go up to a bit before halfway, and some text on the terminal part gets printed on screen, but then it stops and doesn’t go any further than this. No desktop.

I have no idea how to get to a desktop screen from here.

Most of these I can’t help with (as I don’t have any monitors that will accept composite video input) but there is one item I do have an explanation for.

the “loading” animation go up to a bit before halfway, and some text on the terminal part gets printed on screen, but then it stops and doesn’t go any further than this.

This is normal for the first boot of RISC OS on the Pi Zero W. You almost certainly won’t have connected a USB-to-Ethernet adapter, so RISC OS boot will stall forever trying to access the (nonexistent) adapter: the final message on the terminal will be “Contacting DHCP server for Ethernet over USB interface”. Pressing ESC at this point should go through to the desktop.

I have tried pressiing ESC, but the system simply freezes once it gets to the DHCP message.

Is this an SD card known to work on a different Raspberry Pi model, or is this the first time you’ve tried RISC OS on any Pi?

I’ve used this SD card for other operating systems and it worked fine (RasPup, Raspberry Pi OS, BMC64, etc).
I’ve never tried RISC OS before.