@eskimo I was unable to import into "login", "System", or "iCloud" keychains, but was able to import into "accountsKeychainExport". What is that? It seems very sus.
In any case, I have TWO of these "accountsKeychainExport" keychains in my system, and both are empty, even after import.
I had the inspiration to try dragging the .cer file from the Finder into my login keychain, and that seemed to work, but it says the certificate is not trusted:
(I’ve redacted identifying info; note that the selected cert replaces the last cert in that list, set to expire in a month.)
Ah, I had to DL a newer Apple intermediate certificate from here (specifically, the G4 cert). That seems clunky.
macOS 21F79 on M1 Max MBP.