file formats are a nonissue. encapsulate the format and move forward.
interfacing with multiple agencies are a non-issue... just define the gateway objects and move on.
it’s all data storage, data shuffle and business rules.
I’ve found with transaction processing, the most productive system designers were not the best and brightest, but some quiet fat guy in a room by himself who nobody thought was that worthwhile because he still programmed in COBOL.
Of course most decent transaction processing programmers already have back doors to most large systems publicly in use,....because at some point in time they had to connect with them in their transaction processing.
It is difficult enough to tie together 7 or 8 RDBMS into one repository, but to try and develop a website following all the rules of the ACA would be absurd and unnecessary. They will focus on just a few areas of data capture, normalized to their larger system enterprise needs.
I suspect they will first focus on unique identifiers within respective systems, else the rest is garbage.