[erikbye]

There is definitely a higher risk you inhale enough virus progeny indoors than outdoors, yes. We know from the flu that indoors the virus can stay suspended for many hours. Regular talking can project enough virus from an infected person for the air to become sufficiently contaminated, though shedding varies by individual. The more (longer) you breathe that air, the greater your chance of becoming infected. This might also explain why indoors is a greater risk than outdoors, you spend less time in the air that's contaminated, in addition to the greater diffusion/dispersion outdoors, of course.

[newtoday]

Are you saying I could breathe in some, conveying a small amount of the virus, and not get infected? That seems to be the opposite of what highly contagious means.

[erikbye]

Disclaimer: Not a virologist.

A virus has to achieve viral entry: it has to find a suitable host cell, and introduce its viral material.

https://en.wikipedia.org/wiki/Viral_entry

Whether an aerosol hits your face, or you breathe air with suspended particles containing the virus, the virus has several challenges it needs to overcome (described in the link above). Its success is not guaranteed. An increase in virus particles improves its chance while a decrease improves your chance.

In theory, a single virus particle could achieve its goal.