Can't boot from Big Sur installed on a USB I'm trying to install Big Sur on a USB so that I can boot from the separate installation on the usb. Note, I'm not trying to create an installation USB. I followed the directions here and everything worked, except after installation, at the final stage of the boot it just hangs.
I've tried this on a few different macs, and they all hang at the same step. Booting up in verbose mode gives the following final output before hanging (this may be a little off because I used OCR, but I tried to correct what seemed relevant, note in this log it was attached to a thunderbolt port):
...
&lt;date&gt; locathost com.apple.xpc.launchd[1] &lt;Notice&gt;: Early boot complete. Continuing system boot.
ALF, old data swfs pid_entry &lt;ptr&gt;, updaterules_msg &lt;ptr&gt;, updaterules_state &lt;ptr&gt;ALF, old data sufs pid_entry ptr&gt; updaterules_msg &lt;ptr&gt;, updaterules_state
&lt;date&gt; localhost con.apple.xpc.Launchd[1] (com.apple.iomfb_fdr_loader.31) &lt;Error&gt;: Missing executable detected. Job: `com.apple.iomfb_fdr_loader`
Waiting for DSMOS...
dev_init:297: diskl devi accelerated crypto: (compiled @ Jan 24 2021 20:57:23) dev init:300: diskl device_handle block size 4096 block count 122061321 features 16 internal solidstate
nx kernel mount :1134: diski initializing cache w/hash_size 8192 and cache size 32768 nx_kervel_momt:1482: diskl checkpoint search; Largest xid 8330371, best xid 6330371 @ 20
container unload:1497: vnode_close() invoked in the container unload path ALF, old data swfs pid_entry &lt;ptr&gt;, updaterules_nsg &lt;ptr&gt;, updaterules state &lt;ptr&gt;8810018268us
AppleThunderboltGenericHAL::earlyWake - complete - took 8 milliseconds
AppleThunderboltGenericHAL::earlyWake - complete - took 0 milliseconds
IOThunderboltSwitch(100)::listenerCallback - Thunderbolt HPD packet for rid = 1 route = 0x0 port = 9 plug = 1
IOThunderboltSwitch(100)::listenerCallback - Thunderbolt HPD packet for rid = 1 route = 0x0 port = 9 plug = 1
IOThunderboltSwitch(100)::listenerCallback - Thunderbolt HPD packet for rid = 1 route = 0x0 port = 10 plug = 1
IOThunderboltSwitch(100)::listenerCallback - Thunderbolt HPD packet for rid = 1 route = 0x0 port = 10 plug = 1

It seems like maybe the problem is with com.apple.iomfb_fdr_loader but I'm having trouble finding anything related to this erring.
Some things I've tried:

I've tried booting on several different macs (all running Big Sur) and this happens on all of them. So it probably has something to do with the usb or installation.
I've tried reinstalling mac os on the drive several times, and none of them booted so it wasn't a fluke with writing.
I was able to turn this same usb drive into a mac installer drive, and that booted up fine, so it seems likely there's some nuanced flag I forgot to set on the usb.
I tried resetting the parameter ram, but that didn't help.
I tried installing Catalina instead, but all I could find was the dmg for Catalina, and didn't want to go through the process of first writing that somewhere then trying to install it, but that may be my next step if a separate drive doesn't work (see below).

The one thing I haven't tried is seeing if I follow the same process for a different usb drive if I encounter the same issue. That should at least narrow it down to the process of installing or the image itself.
Updates
Using a different device with the same image did work, so it seems like this is a hardware problem with the usb device. However, I've been unable to get this to work with multiple different usb-c devices.
Catalina also worked, so this seems to be something funny with Big Sur.
I've also be unable to upgrade from Catalina to Big Sur once the installation is working.
Get a new drive. That process is quite a bit longer than needed, but it’s correct. If you have errors with the install it’s likely these are the causes in order:

Bad USB storage
Bad download of the installer (very unlikely, but it happens)
Not following the guide
Failure of the Mac (more likely USB port or cable or hub)

Catalina is probably a safer bet for this activity for another couple months - Big Sur is still getting some edge cases patched up. So maybe get that downloading the next time you can let it run.