Apart from Bison, depository FATCA-compliant services are also offered by BiG and Atlantico Europa (necessary for US investors going for the fund route). BiG has been offering these services longer, so probably a safer option. Bordr.io can indeed help with opening an Atlantico bank account ($10 off the price with NOMADGATE code). Millennium does not offer depository services for US investors.
I double-checked with Bison, and they have set a cut-off date of November 5 for new bank account openings for GV investors wanting to complete their GV application within this year. This means that the person applying for a bank account needs to have a NIF number already and all the original forms and certified copies of the documents need to arrive at their offices latest by November 5. If someone doesn’t have a NIF number, they will get refused already now considering the time constraints.