[wddkcs]

I'm not familiar with any country that mandated or adequately supplies n95s to their citizens.

There's a the question of whether masks can be effective (even without a study, common sense says they are against a respiratory virus) vs. the question of whether they are effective, given actual use.

There's a good argument that idealized use of masks would have been beneficial, but actual use was likely neutral, or even counter productive (caused more unintended harms than prevented infections).