How to copy the "Local Items" Keychain to a new mac?
FYI: I just managed to get my keys to my new mac (this only works if you still have access to the old Mac and can boot it up):


(on the old mac) Remove your current user's password
Create a new keychain (without a password)
Copy all keys in "Local Items" to your new keychain
Copy the keychain to the new mac
(on the new mac) Remove your current user's password
Add the new keychain file
Copy all keys in the new keychain to "Local Items"
Delete the new keychain
Don't forget to set a password again after that


It's a bit annoying as you have to click "Allow" for EACH item in the keychain but well, it's the only thing I found that works.