something along the lines of this in your app code:-
library(googlesheets)
# to setup googlesheet auth (comment out once done) -----------------------------------
#shiny_token <- gs_auth() # authenticate w/ your desired Google identity here
#saveRDS(shiny_token, "shiny_app_token.rds")
googlesheets::gs_auth(token = "shiny_app_token.rds")
sheet_key <- "your_google_sheet_key_here"
df <- googlesheets::gs_key(sheet_key) %>%
gs_read_csv(ws = "worksheet_to_read")
Store the shiny_app_directory.rds in the shiny app parent directory and be sure not to upload it to github!