Earlier quoted context omitted.
Nations exist to protect it's citizens. So yeah, as they should, each country is prioritizing their own needs before exporting any surplus to other countries. The challenge is no one really has any idea how much of the supplies they actually need. It's interesting to me that you find this surprising or view it as bad behavior.
States use serving a “nation” as a retroactive justification for doing what they have always done. In a global crisis, selfish actions help nobody.
Officials are elected to serve the need of their own constituants first and foremost, not foreign interests. There is nothing selfish about that. The American government doesn't have to consult with Canada or Mexico before taking a decision in times of crisis. This is the very core idea behind a representative democracy.
Where politicians failed is with their lack of foresight when it comes to stocking masks and ventilators, they didn't fail because they were "selfish" toward other nations.