Multilanguages APP: add drop-down list to select a language

Hi Guys!!
I would like to use the shiny.i18n to translate an app in multiple languages
Following the examples in the package website Shiny Applications Internationalization • shiny.i18n
I was able to build a translation file and select the target translation language using i18n$set_translation_language method.
However I would like to create various instances of the app with different languages by adding a dropdown list to select the language.
In the package website two options are proposed for the live language exchange (Introduction to shiny.i18n • shiny.i18n), both using a fluidPage.
Instead, I would like to use the live language exchange with the navbarPage but I was not able to code it properly.
I am very new to shiny and any help is really appreciated

Below you can find a the structure of my basic app

Thank you in advance

# Load libraries ----

# Define the json file used for translation ----
i18n <- Translator$new(translation_json_path = "translations/translation.json")
i18n$set_translation_language("es") # run an instance of the app with a specific language (e.g. es)

# Define UI ----

ui<-navbarPage(title =  i18n$t("Website title"),
               tabPanel(title =  i18n$t("tab 1"), 
                        "content 1"),
               tabPanel(title =  i18n$t("tab 2"),
                        "content 2"),
               tabPanel(title =  i18n$t("tab 3"),
                        "content 3"),
               tabPanel(title =  i18n$t("tab 4"),
                        "content 4")

# Define server logic ----
server <- function(input, output,session) {


# Run the app ----
shinyApp(ui = ui, server = server)