Once approved, they open the account, and can report it. Non-use of the card wont prevent reporting. Hopefully, they will simply not report.
If it is reported, the negative impact will be reduction in your average age of accounts due to addition of an account with zero age..
Depending upon your current avg age of accounts, that might have a negative score effect. Closing of the account wont remove it from continued inclusion in your AAoA calculation.
If they do report, I would request them to delete. Deletion would have advantages to them in that it would remove the account from any need to maintain active records, update the account show any changes occur, or to answer any FCRA disputes that the consumer might initiate.
