The vaccines kept those vulnerable parties from dying. The fact that vaccinated people had less severe cases isn't theoretical it is extremely well studied. It was reasonable to suppose it would slow the spread as less chance of infection means less chance of spreading it but factually vaccinated people were much more likely to take risks ergo this certainly more than canceled out benefits in that respect.
Also your concept that Biden killed millions is just un-mathmatical. The total deaths in the US after Biden took office is ~800,000. There aren't millions of deaths to lay at his feet period and laying even those 800k at Biden's feet is nonsense. Logically if you want to explore the impact of the president you would have to compare not vs a fantasy world in which there is no covid but a hypothetical one in which an alternative Biden made better choices with justification as to how your counterfactual is both foreseeable AND actionable.
For instance it makes no sense to ask 2021 Biden to act on scientific insight earned in 2023 or enact policies which is out of scope of his power, illegal, unconstitutional, or up to the states.
By forcing people to vaccinate or lose their jobs, people just wholesale discounted the entire pandemic rather than take other meaningful precautions.
It is profoundly weird to blame the left for conservatives refusing to protect themselves or others and blame their entire weird psychotic philosophy with its own proponents, memes, influences, and twisted perception of the world on the lefts vaccine mandate. Relatively few actually lost their job and the the entire movement pre-existed covid and only gained additional adherents and credence.
Also by the time Biden came into power n95 was already promoted as better unless you think Biden is at fault for not getting Trump's regime to promote better masks.
To recap
1.2M died since 19ever not millions
Of those 800k died after Biden took office.
It's not clear that many could have been saved by superior federal policy.
Your claim that Biden's actions led to the deaths of millions appears to be your fantasy unsupported by any objective reality because you are both scientificly illiterate and don't even know how many people died.