The latest Sonoma version does not work(read boot) with OCLP 1.0.1The OP has a system that is now "Not Usable", with OCLP 1.2.1. I actually suspect that there is a hardware issue involved, because that display corruption came back after getting the system up and running again.
In this case, a clean install booting from a OCLP 1.0.1 USB may work best, wiping the target disk with Disk Utility.
Why do you think using OCLP 1.0.1 will make the iMac 13,1 non-bootable? Does that model have issues with Sonoma?
Or with OCLP?

