Home Forums FineTunedMac Community Lounge First Look At Big Sur

Is the system volume actually MORE untouchable in Big Sur than it is in Catalina, i.e. has it been fixed so it can't be manipulated from a clone as I do in Catalina (like booting into OS 9 to manipulate the early versions of OS X)?

Yes, it's cryptographically sealed and then a snapshot is taken. On startup, the snapshot is mounted and that's what the system boots from – the original System volume isn't even mounted. If you mount the System volume and make changes to it, that renders the system non-bootable. You can learn more about it here:

https://developer.apple.com/news/?id=3xpv8r2m

There is actually a mode in which you could modify the system and create your own snapshots, but that's geared towards kernel extension developers.