It appears your OCLP installation is not working (unsupported device):
May 3 13:27:40 iMac osinstallersetupd[215]: : 052b2000 : Mac-F2238AC8 is not in the list of SupportedDeviceModels
May 3 13:27:40 iMac osinstallersetupd[215]: : 052b2000 : Unable to install due to unsupported device: Error Domain=BIErrorDomain Code=2 "(null)"
May 3 13:27:40 iMac osinstallersetupd[215]: disk0s2: isUpdateInstallable: NO: BIPreflightError - Domain: com.apple.BuildInfo.preflight.error Code: 9 UserInfo: {
NSLocalizedDescription = "The update cannot be installed on this computer.";
NSLocalizedFailureReason = "The update cannot be installed on this computer.";
NSUnderlyingError = "Error Domain=BIErrorDomain Code=2 \"(null)\"";
}
Are you certain you booted the OCLP EFI? What version of OCLP is installed?
Yes I booted off the external drive that I built with BS 11.2.3 and the latest try I used patcher 0.4.11 ( the latest one for Big Sur)