Hide Keys in Shiny Application Deploy

Perhaps this solution is too basic, but you can simply create a .txt file, with the keys in it one per line. Than you can use scan() to read that file.

Something like:

   Sys.setenv("AWS_ACCESS_KEY_ID" = scan("file.txt",what="character")[1],
           "AWS_SECRET_ACCESS_KEY" = scan("file.txt",what="character")[2],
           "AWS_DEFAULT_REGION" = "us-east-2")

It is similar to the first solution in the "managing secrets" link in the comments, except that we use a simple text format instead of JSON.