Did not post if Clover or OpenCore. I would use Clover but I could never get BS or Monterey to work with Catalina so I pass on that. For me OC has turned out to be easier to use then I expected, particularly when constructing the EFI from within macOS. Now several versions into OC with no particular insight other than OCD pays off when constructing an OC EFI.
If you post your EFI someone who actually understands these things might go over it for you. The most common issues I see posted everywhere:
If Catalina is working then presumably motherboard UEFI settings are correct.
A common problem installing Monterey seems to be not preparing a custom usb kext, so if you didn't you need to in Catalina. USBinjectall kext may not work at all, might activate 1 or 2 motherboard USB 2 ports. If your custom kext works in Catalina it will work in BS and Monterey, Clover or OC. Bluetooth can be problematic but worry about that when you get there.
For Monterey on OC be sure to use the latest version, latest kexts, use pre-made files and triple check all configp settings. Your stuff should work with generic drivers/kexts et al apart from the custom USB kext. Use the recommended SMBIOS, in my not unlimited experience OC is not as pliant about the SMBIOS as Clover. I assume you know you can/should use the same identifiers as you are using in Catalina if going to boot Monterey on the same machine. I always do.
I generally do what I think you are doing, installing/updating from a current macOS install to a new SSD--it won't work for Monterey if not using a Monterey compatible EFI in Catalina (the same EFI will/should work with both OSes). If constructing a new OC EFI obviously you check that it boots from a USB key stably before copying to an SSD.
