I am admittedly out of touch with OFAC related sanctions, so this question may come off as naïve.

I'm poking around treasury.gov resource center and came up with the below excerpt. My knee jerk reaction, before reading this, is that money can not come into a US based FI from Iran. The below seems to point to a contrary view.

Set me straight. Any pointers on the best way to find these answers (BOL speed).

Source: https://www.treasury.gov/resource-center/sanctions/Programs/Documents/implement_guide_jcpoa.pdf

A. Financial and Banking-related Sanctions
Commitment:
Section 4.1 of Annex II and section 17.1 of Annex V of the JCPOA provide for the lifting, on Implementation Day, of secondary sanctions that apply to non-U.S. persons who engage in certain financial and banking activities related to Iran. In particular, beginning on Implementation Day, the following activities by non-U.S. persons are no longer sanctionable:
• Financial and banking transactions with individuals and entities set out in Attachment 3 to Annex II of the JCPOA, including: the Central Bank of Iran (CBI) and other specified Iranian financial institutions; the National Iranian Oil Company (NIOC), the Naftiran Intertrade Company (NICO), the National Iranian Tanker Company (NITC), and other specified individuals and entities identified as the Government of Iran by OFAC; and certain designated individuals and entities that were removed from the SDN List on Implementation Day (see section 4.1.1 of Annex II of the JCPOA);

While there are some exceptions, most OFAC sanctions are not all or nothing for a particular country but address certain entities and individuals.