They already sell cars with a bioweapon defense mode.

Who does that? Seriously asking, even if I can imagine the answer already...

Tesla does: https://futurism.com/the-byte/tesla-wildfires-bioweapon-defe.... It's an optional upgrade. I ordered it for my Model S because, at the time, Hawaii was experiencing really bad VOG, which my girlfriend was extremely sensitive to. On bad days, she could retreat to the Tesla, activate BioWeapon Defense mode, and experience some relief.

I mean... a good respirator is like $30-40. Significant savings over a Model S, and you're not stuck in the car. But I suppose wearing a mask can be uncomfortable.

Tesla. It is unnecessary in almost all circumstances, but a lot of people have raved about it when dealing with California's wildfires for example.

Ah, so they covered B and C weapons. What about A and hardened electronics?

Tesla, it's an option in the Model X's climate controls.