The new machine is the same year, so is unsupported Monterey. What I'm hearing is something I actually didn't consider. Reinstall Monterey onto the machine on a separate partition. Then run the Patcher. Then I might be able to boot to the partition I need access to?
Sorry, I'm not sure what you mean about "reinstalling Monterey onto the machine on a separate partition."
I don't think that anybody's giving you that advice. Below I think is a good checklist of what you need to do and what order you need to do it in, if you are planning on using this SSD exclusively in the new machine, and you want to try to keep all of your apps, files and settings as is.
1) have a file back up and Time Machine backup.
2) prepare a Monterey install opencore USB stick that has been configured for your new target machine.
3) roll back/ remove patches from your previous install and most importantly remove the previous open core configuration from your SSD’s EFI. If you know how to do this manually, you can just mount your EFI, and remove from the EFI what you need to remove. The OCLP website has a section about uninstalling opencore. You can follow that. You need to get the old opencore conig off of your ssd‘s EFI partition. When you reinstall Monterey in the next step below, that should automatically overwrite the existing patches, so you might not even need to rollback the patches from your previous install. Since you can’t boot to Monterey normally with the SSD inside the new target machine right now, you can do step #3 with the ssd back in the previous machine, or you can use a SATA <> usb connector and remove the files from your SSD hooked up externally to a different Mac. You must get the opencore config files from your previous install off of your ssd’s EFI partition before moving on to step #4. The reason why your SSD won’t boot right now in the new machine is because of what
@Ausdauersportler wrote in post #5,803 point 1. The first step in fixing this is to remove the old OCLP configuration from your SSD’s EFI partition. This configuration lives on your SSD’s EFI partition.
4) put the SSD in the new target machine, reset the nvram in the new machine, and install Monterey with the USB stick, using the well-known path, that is documented on the OCLP website. However, make sure to install the new copy of Monterey on top of your old copy of Monterey. On the same partition. This will preserve all of your files, apps, and settings, and install Monterey using some new machine specific settings and overwrite some of the old machine specific settings.
5) Do post install patches / move new EFI from USB to your SSD’s EFI partition. This part is also well documented.
The above path will give you the greatest chance of preserving all of your files , apps ,and settings. Good luck.
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