OpenCore

How to test EG2 vBIOS version without iMac firmware EG2 mod

Within the EG2 subfolder you can find both EFI drivers fetched from an 2017 iMac firmware named CoreEG2_x64.efi and EDIDParser_x64.efi.

Simply add both files to the Drivers folder of your OpenCore installation. For each driver add entry within the config.plist to the OpenCore UEFI/Drivers section next to OpenCanopy. The addition to the config.plist would look like this, here you see the CoreEG2_x64.efi and EDIDParser_x64.efi entries added in UEFI/Drivers

                        <dict>
                                <key>Arguments</key>
                                <string></string>
                                <key>Comment</key>
                                <string></string>
                                <key>Enabled</key>
                                <true/>
                                <key>Path</key>
                                <string>EDIDParser_x64.efi</string>
                        </dict>
                        <dict>
                                <key>Arguments</key>
                                <string></string>
                                <key>Comment</key>
                                <string></string>
                                <key>Enabled</key>
                                <true/>
                                <key>Path</key>
                                <string>CoreEG2_x64.efi</string>
                        </dict>

OpenCore will load these drives after disk access instead loading both drivers during the early the boot process. Since the EFI Boot Picker has already passed when OpenCore can load those drivers you cannot get the EFI Boot Picker working this way. But the graphics card flashed with EG2 drivers will work and can be tested.