Oh, I missed that it was per RTN, and just focused on the "that can receive debits" part; yeah, that's super cheap then, particularly since they don't take a percentage of the transaction value and it has a default maximum transaction limit of $100k.
I'd like clarification but from the wording and this release, it seems that it's about $0.05 per transaction and the bank has to pay a $25/mo fee per routing number: https://www.pymnts.com/news/faster-payments/2022/fed-release...