Or, they could run their own fabrication facilty, where they can exert total control over the production line, in total secrecy, and you'd never know the difference, or notice a sacrifice in the fidelity of replication.
Think that's impossible? Not at the nation-state level. Not in communist countries where everything is property of the government by default. Not in capitalist countries like the United States, where entire nuclear facilities are replicated in secret. [0]
Not in capitalist countries like the United States where you can just contract a manufacturer to produce the board you want. Even parts acquisition becomes a job to be done. As long as the producer dosn't know (or even does know but can be silenced at the right level) then really, once the actual design is in hand and assuming the parts aren't too hard to get there's little to stop someone from producing a board just like a board produced elsewhere.
Think that's impossible? Not at the nation-state level. Not in communist countries where everything is property of the government by default. Not in capitalist countries like the United States, where entire nuclear facilities are replicated in secret. [0]
[0] https://www.businessinsider.com/the-us-built-a-secret-replic...