That's why I created that "easy to install package".
You still have to disable SIP by yourself, learn how to mount EFI partition, etc. But I insist that's mandatory for any OpenCore to learn. Just in case, if anything goes wrong, the user still has the basic knowledge to perform some necessary recovery actions.
Anyway, if you want to play safe, after you download my OpenCore 0.6.3 package, you can follow the steps in this video to install OpenCore onto a USB thumb drive. So, if that doesn't work as expected, you can simply pull out the USB drive, then nothing is changed.
Of course, you don't need to install Big Sur (which the video just want to demo that my package also enable Big Sur support on the 5,1). But if you want to run the latest FCP, you have to go beyond Mojave (e.g. Big Sur).