Most national reserves are managed by central banks. In the United States, the Fed is the national reserve management agency of the United States and is an independent organization and not subject to the control of the United States government. So Trump or any politician who wants to add bitcoin to the national reserves would need to bring the proposal to Congress for a vote.

It is safe to say that there is no other viable solution than convincing the parliament and needless to say, we all know how time consuming and difficult that will be. To be fair, a bitcoin reserve strategy could still become a reality, but it would take a long time and possibly even decades.