I was doing installs from the Ventura download and the recovery partition. My last attempt was via the recovery partition. I can’t see why it would matter, but this certainly seems like a bug, so who knows

I have the same exact issue. I called Apple support, but they ended up telling me that it's not a supported configuration and if it doesn't work there is nothing else they can do. It's very unfortunate. This worked fine on my Intel Macbook Pro. I hope it's just a bug in Ventura and it will get patched. Annoyingly, we can no longer even install a previous macOS version, and even if we do get an older macOS version, it won't boot on an Apple CPU mac with a newer macOS version. How are folks testing different macOS versions? Do you have to get several macs now? https://discussions.apple.com/thread/254921596