Shiny app: nothing changes when clicking on action button - r

Question

Building on multiple stackoverflow questions, I tried to build this app which contains two action buttons the first one shows a data table the second one should open another sourced app but actually, nothing changes but in the global environment all list, functions, and dataframes are reflecting.
the used code.
#UI.R
library(shiny)
library(shinydashboardPlus)
library(DT)
library(readxl)
library(dplyr)
library(formattable)
library(shinydashboard)
library(shinyjqui)
library(shinyjs)
library(shinythemes)
library(markdown)
title <- "emblem"
ui = fluidPage(theme=shinytheme("superhero"),
dashboardPage(dashboardHeader(title = title, titleWidth = 200),
dashboardSidebar(selectInput("listofitems","Items List",c("Home","Group","Clients"), selected = "Home")),
dashboardBody(
useShinyjs(),
uiOutput("ui_myHome"))))
#SERVER.R
Clientsbutton<-fluidPage(theme=shinytheme("yeti"),
DT::dataTableOutput("mytable"))
shinyServer(function(input, output, session){
output$mytable = DT::renderDataTable({
mtcars
})
output$ui_myHome<-renderUI({
if (input$listofitems == 'Home'){(fluidPage(
widgetUserBox(title = "Clients",
shiny::actionButton(inputId='clientsmainbuttonId', label="Click here"),
type = 2, src = "https://adminlte.io/themes/AdminLTE/dist/img/user7-128x128.jpg", color = "yellow"),
widgetUserBox(title = "Group",
shiny::actionButton(inputId='GroupbuttonId', label="Click here"),
type = 2, src = "https://adminlte.io/themes/AdminLTE/dist/img/user7-128x128.jpg", color = "green")))}
else if (input$listofitems == 'Clients'){(Clientsbutton)}
else if (input$listofitems == 'Group'){(source("testsource.R",local = T)$value)}
})
observeEvent (input$GroupbuttonId,{
#browser
source("testsource.R",local = T)$value
})
observeEvent(input$clientsmainbuttonId,{updateSelectInput(session,"listofitems","Items List", choices =c("Home","Group","Clients"), selected = "Clients")},ignoreInit = TRUE)
observeEvent(input$logo,{updateSelectInput(session,"listofitems","Items List", choices =c("Home","Group","Clients"), selected = "Home")},ignoreInit = TRUE)
})
#TO BE SOURCED APP
File name testsource.R
rm(list = ls())
library(shiny)
shinyApp(
ui=shinyUI(basicPage(
actionButton("go", "Go"),
numericInput("n", "n", 50),
plotOutput("plot")
)),
server=shinyServer(function(input, output, session){
randomVals <- eventReactive(input$go, {
runif(input$n)
})
output$plot <- renderPlot({
hist(randomVals())
})
})
)