Hi Eloise, I think that the next MoodleBox Image will be based on the new Raspberry Pi OS with Debian Bookworm. And this image will also work with the Raspberry Pi 5. The current MoodleBox image is based on Debian Bullseye and this software does NOT work with the Raspberry Pi 5.
I can‘t say if I would use the Raspberry Pi 5 as a MoodleBox. It need much more electrical energy than a Raspberry Pi 4. Also it costs more money. Yes, I will get a Raspberry Pi 5 and I will test it with the MoodleBox software. But I think that the Raspberry Pi 4 has enough power to host the MoodleBox.