Good info. Under what circumstances does one have to bless the OpenCore EFI as mentioned in the instructions in the 1st Post ?For info, with the native Apple Startup Manager, there is no need to use Recovery mode etc to bless OpenCore.
All he need to do is just hold Option to boot, at the Apple Startup Manager, select the OpenCore EFI entry, then press Control + Enter to select it. This will bless that EFI entry (which should be OpenCore).
Not quite sure I understand what you mean by "this method is OS version independent".This method is OS version indepedent, therefore, works better for cMP that only has natively unsupported macOS installed.
If you mean using the native Apple Startup Manager selecting (and effectively blessing) OpenCore EFI entry then of course yes that's OS independent.
But using a native Apple Startup Manager does not allow one to successfully select and boot an unsupported macOS natively since....well it's unsupported; e.g. Monterey. That is, first time, one has to select OpenCore EFI and then any macOS from OpenCore's boot picker.