如何在`selectiseInput`中设置文本，该文本不在代码的选项中

library(shiny)
library(shinyWidgets)

ui <- fluidPage(
  selectizeInput(
    inputId = "mySelect",
    label = "选择一个选项：",
    choices = NULL,
    selected = NULL
  )
)

server <- function(input, output) {
  
}

shinyApp(ui, server)

library(shiny)
library(shinyWidgets)

ui <- fluidPage(
  selectizeInput(
    inputId = "mySelect",
    label = "选择一个选项：",
    choices = NULL,
    selected = NULL
  )
)

server <- function(input, output) {
  observe({
    updateSelectizeInput(
      session = session,
      inputId = "mySelect",
      choices = c("选项1", "选项2", "选项3", "文本")
    )
  })
}

shinyApp(ui, server)