nvram -p with amfi variables are right, at this point I guess or some drive issues (you might try a Diskutility First Aid on your .4 beta1 disk) or during your previous OTA .4 beta1 something went wrong, anyway just retry booting in .4 beta1 single user mode (with replaced output ASentientBot wrappers):
Code:
mount -uw /
update_dyld_shared_cache -force
mount -uw /System/Volumes/Data
chown -R 0:0 /System/Library/Extensions/
chmod -R 755 /System/Library/Extensions/
kextcache -i /
kcditto
reboot
after the next reboot don't use the "-v" verbose mode, just boot with apple logo (because it shows the Remaning time message), and let it run for at least 15 minutes maybe post-OTA should complete its post-scripts on the Catalina Data Volume.
To me after my OTA update with Catalina logo installing (about 45 minutes), before autorestart 30 seconds showed a similar message "Now system restart to continue update the
Catalina Data Volume", followed a simple apple logo booting with "remaining time" that took about 30 minutes to complete on SSD.