This is all fantastic, thank you very much for preparing such a comprehensive resource for organising and running this activity! I'm pitching a reprohack to the UW eScience community for the Winter quarter, and have been studying your materials in preparation for when we set a date.
When I deployed my Shiny app, I found that I didn't have an .httr-oauth file, but I had a .secrets file in my repo. I needed to ensure that got sent to the Shiny server (instead of the .httr-oauth file) to make it all work. Not sure it that's because I'm doing something wrong here, or there are multiple ways that Shiny works?