From the final rule preamble for Reg DD
Comment 11(a)(1)-2 explains that the aggregate fee disclosures must be provided on periodic statement for all accounts to which an advertisement promoting the payment of overdrafts applies. Accordingly, if an institution specifies the types of accounts for which the overdraft service applies, the institution is not required to provide the disclosures for other types of accounts offered by the institution. An institution is required to provide the new aggregate fee disclosures for all of its accounts, however, if the institution generally promotes the payment of overdrafts without specifying the accounts to which the advertisement applies.

Doesn't the requirement for aggregating apply to any account types for which we offer ODP? (and not just to accounts for which customers have signed up for ODP)

I agree with your read. It applies to any account that the ad applies to, regardless of whether the depositor has ODP coverage.