I have finally found the Windows progress bar hidden algorithm!!

windows_update.R

update_windows <- function() {

  pb <- progress::progress_bar$new(
    total = 100,
    format = "(:spin) :what [:bar] :perc",
    clear = FALSE,
    width = 80
  )

  i <- 1
  p <- numeric(1)

  usethis::ui_info("Windows is updating")
  usethis::ui_info(
    "Updates are underway to keep things running smootly!"
  )
  usethis::ui_todo(
    "Please, keep your computer on and plugged in."
  )
  on.exit({
    cat("\n")
    usethis::ui_done("Updates completed!")
    Sys.sleep(3)
    usethis::ui_stop("NO PANIC!")
  })
  while (TRUE) {
    p[[1L]] <- round(1 - 1/i, 2 + log10(i))
    pb$update(
      p,
      tokens = list(
        what = "We are quite there!",
        perc = paste0(100 * p, "%")
      )
    )
    Sys.sleep(0.4)
    i[[1L]] <- i[[1L]] + 1L
  }
}

update_windows()