How do you press
Alt on a Mac? It doesn't have an
Alt key. Are you talking about a Hackintosh with a Windows keyboard?
You do not bypass OpenCore by holding down the Option key at boot up, that is how you get the Open Core boot picker.
In fact you have to press the Option key to get the Open Core boot picker, then first select (Tab key) the EFI icon and hit Enter (or mouse click) to boot the unsupported Mac. Then when the screen shows your bootable disks, choose the target disk (Tab key again) and hit Enter (or mouse click). When you hit Enter to boot the target disk, hold down the
Shift key to get into safe mode. Unfortunately, the latest OCLP versions seem to have trouble with that function, depending on the hardware, as seen in this thread so many times. My iMac 15,1 is immune there (Whew!).
Experience macOS just like before
dortania.github.io