There is also a search on the landing page: https://reproduction.live which I should probably put in the sidebar of the dashboard page as well.
In the UK, epidemiological modelling is done by various government bodies and universities, and it is this that is being reported in OP:
tl;dr is that we use a single datasource (not managed by us but by many dedicated others) and use case counts to estimate number of currently infectious and from that we estimate R. The running time of our R estimation calculations for all regions is around 1.5 hours on a $10/month Digital Ocean droplet.
Sometimes strange looking results on our site picked up by guests can be fed back to the maintainers of the datasource resulting in a correction of the data.
On our website, R value estimation is done by my father, a retired computer science professor with a long history of mathematical modelling experience. This is hacker news right? :)
It might be possible to build up a list of regions as you navigate through the site, and then show only those in the bubble chart so that you can compare them. Interesting idea.
We wouldn't be able to aggregate infectious or R estimates for one or more regions together as the computation for those is done during deploy and then that processed data is uploaded along with the static site (it doesn't connect to a database to fetch data on the fly).
Plausible.io tells me that for today for the spike from this comment, 70% of users were on mobile. I might try the rotation thing. Thanks for the feedback!