I think you really need to study the first message of this thread. Rightly configured, OpenCore will let you install and run Big Sur if your unsupported Mac has the right setup (like a Metal GPU, sufficient RAM, et cetera), but I don't know how it will behave if your Big Sur installation has been compromised by using third-party procedures, such as the so-called "micro patcher". In case you do manage to boot your current non-pristine Big Sur through OpenCore, perhaps you should download the latest untouched full installer of Big Sur 11.2.2 and then install that on top of your current Big Sur installation. Hopefully, that will get rid of your current patched, unsealed Big Sur and generate the correct, sealed APFS structure where an untouched system will behave as intended.