database of user API keys

I'm creating a set of shiny apps that will privately hosted on shinyapps.io. The apps require at least 3 different API keys to access various data sources. I would like to use user-specific API keys, in which the user logs onto shinyapps.io, then all of the shiny apps have access to that user's API keys for these data sources (e.g., AWS s3). I do NOT want to just embed my own API keys into each shiny app.

How does one do this with shinyapps.io? The shinyapps.io documentation is lacking in regard to including user-specific "secrets". I was hoping that secrets could be added in the shinyapps.io user settings, similar to adding secrets in GitHub; however, it appears that a user can only create a token for rsconnect.