I wanted to do a clean install on my shiny new M1 MacBook Pro, running macOS 11.1. I booted into recovery mode and navigated to disk utility, click my Macintosh HD entry, erase, then erase volume group.
Reformatting done, I selected "Reinstall macOS Big Sur." This progressed normally, and I was eventually greeted with setup assistant, asking me to select a language.
Everything works normally, up until I reach the "Create a computer account" dialog. No matter what information I enter here, the setup assistant freezes for 5-10 minutes . It eventually reports that creating the account failed, with no further information. It asks me to try again - if I try to use the same short or full account name, it complains that the short or full name is in use and to select something else. If I change the full and short names and try again, the same thing occurs.
If I forcibly shut down the machine at this point and reboot, I am greeted with a normal login menu - e.g. no setup assistant. The accounts that I tried to create using the setup assistant are all listed, but I am unable to log into any of them - seems the password might be set to something other than what I specified.
If during the setup process I signed into iCloud (I have tried with and without signing in), I am given the option to reset the account password using my iCloud account - but this does not work, it shakes a bit as if the iCloud password is wrong. (The iCloud password works perfectly fine on another machine.)
I would write the whole thing off as a glitch, but it is 100% reproducible (on this machine, at least - I am afraid to try my existing machine for the moment). That is, erasing the hard drive and restarting the entire process results in the same errors. If there was a hardware issue, doesn't it seem more likely that we'd run into different set of problems each time?
So, wall of text finished: has anyone run into this, or have any advice on debugging?
I am on attempt 5+ at the moment.
 I can still bring up the Force Quit dialog, and adjust brightness/etc using the Touch Bar.