used on a smartphone, shiny interactive plot doesn't understand finger movements

I have a R-Shiny application with a plot that implements interactive actions: click, hovering (hovering is passing the mouse over the plot, which can be detected by shiny). To give an idea, I post below a simplified shinyapp with the functionnality that is problematic to me, the interactive drawing plot. (it's taken from an old answer of mine here)

It's actually working fine, however I need people to use it from their smartphones. The problem: the finger movements we do in the smartphone are interpreted by the phone as zooming on the page or scrolling on the page, and not as mouse selection or mouse movement over the the plot (hovering).

Is there a modification of the code (java? css?) that I can implement on the app to turn touch events into mouse events, or an option/gesture on the smartphone to enable a mouse-like movement?

Thanks a lot. Code:

library(shiny)
ui <- fluidPage(
  h4("Click on plot to start drawing, click again to pause"),
  sliderInput("mywidth", "width of the pencil", min=1, max=30, step=1, value=10),
  actionButton("reset", "reset"),
  plotOutput("plot", width = "500px", height = "500px",
             hover=hoverOpts(id = "hover", delay = 100, delayType = "throttle", clip = TRUE, nullOutside = TRUE),
             click="click"))
server <- function(input, output, session) {
  vals = reactiveValues(x=NULL, y=NULL)
  draw = reactiveVal(FALSE)
  observeEvent(input$click, handlerExpr = {
    temp <- draw(); draw(!temp)
    if(!draw()) {
      vals$x <- c(vals$x, NA)
      vals$y <- c(vals$y, NA)
    }})
  observeEvent(input$reset, handlerExpr = {
    vals$x <- NULL; vals$y <- NULL
  })
  observeEvent(input$hover, {
    if (draw()) {
      vals$x <- c(vals$x, input$hover$x)
      vals$y <- c(vals$y, input$hover$y)
    }})
  output$plot= renderPlot({
    plot(x=vals$x, y=vals$y, xlim=c(0, 28), ylim=c(0, 28), ylab="y", xlab="x", type="l", lwd=input$mywidth)
  })}
shinyApp(ui, server)