I wouldn't think that OPM would have lots of credit card numbers to hack. Sure, there's information on lots of people there, but who has use a credit card associated with OPM? Why would it be in their system?
It's not the OPM, but a couple of years ago I was randomly selected at work for an independence audit (darn AICPA rules). Part of the audit required me to provide the account information for every financial account that I had.....brokerage accounts, investments, loans, credit cards, bank accounts, etc. for not just myself, but for my wife and all my kids as well. They need to make sure that I don't have any unallowed financial relationships with any audit clients. I don't think they retained that information outside of the audit, but I don't rightly know. I can imagine that the federal government might have to do the same types of audits for people involved in the purchasing/government contracting/contract approval process to root out graft and bribes. So there "might" be that information available, I think?