[dnanian]

In some cases, asr or the OS is not rebuilding the dyld cache, which is why you're getting the boot panic. It should be...but sometimes isn't. We're hoping they're going to fix it.

The secure token should get created automatically when the password is set for the user...and the OS is going to import the password (and, one would expect, the token) when the OS is reinstalled - it's just a basic install. Again - Apple has continued to work through bugs in this stuff over time, but it's quite obviously not a priority for them.

I've never seen "registry root held busy"...and I don't think any of this has to do with HDD or SSD (but do, generally, recommend SSD these days).

Remember: on Apple silicon, you cannot copy the OS into the system at all - only out. As such, a full restore is going to be preceded by a clean OS install internally, followed by selecting 'restore' during first boot.

When you do that, the secure token is properly created by the process...so even if the external boot doesn't work, the restoration will be successful (assuming the backup is a "Backup - all files", with either Erase, then copy or Smart Update...and it doesn't even need an OS on the backup.