A ton of masks used in the US were assembled in China, because they have the manufacturing capacity and labor cost advantage, even if they were built with meltblown filters produced in the US.

If the goal is pandemic preparedness, it would probably be most efficient to just build and mothball production lines, doing limited runs yearly to exercise the machinery.

The government has more than enough land and warehouse space.

As far as I understand, none of the components (or machinery to produce them) are particularly cutting edge... just limited because they were sized for pre-pandemic sales volume.