How to Switch Between NavBar Tabs with a Button R Shiny

You can use updateTabsetPanel to switch between different tabPanels. See the documentation and example codes at https://shiny.rstudio.com/reference/shiny/latest/updateTabsetPanel.html. The code below should fulfill your requirements.

ui <- navbarPage('Test App',id = "inTabset",
                 tabPanel(title = "Panel 1", value = "panel1", 
                          actionButton('jumpToP2', 'Jump to Second Tab')),
                 tabPanel(title = "Panel 2", value = "panel2", 
                          actionButton('jumpToP1', 'Jump to First Tab'))
        )

server <- function(input, output, session) {
    observeEvent(input$jumpToP2, {
        updateTabsetPanel(session, "inTabset",
                          selected = "panel2")
    })

    observeEvent(input$jumpToP1, {
        updateTabsetPanel(session, "inTabset",
                          selected = "panel1")
    })

}

shinyApp(ui, server)