Boy, it's been quite a while! Have a half-assed conclusion (/retrospective/answer).
Here's an article with a lot of illustrations whose models suggest that increased ventilation (in several common scenarios) results in a reduction in infection rate by a factor of about 5-7x, even when compared to mask wearing.
A room, a bar and a classroom
https://www.microcovid.org/ 's model seems to be using a 5x reduction number for indoor vs "almost-outdoor," which seems to roughly line up with this.
For comparison, mCov's factor-reductions for surgical-mask wearing are 2x, and n95s are 10x. So "open-windows and heavy ventilation" lands basically right between the two in reducing risk.
My impression at this point is that adequate ventilation was a pretty strong target for reducing spread.
So... Kudos or BayesPoints to ChristianKI (whichever you prefer) for calling that 8 months ago.