We can use MessagingCenter for this. In your first page, subscribe a message:
public FirstPage()
{
MessagingCenter.Subscribe<SecondPage>(this, "StartProgress", (sender) =>
{
StartProgress();
});
}
public void StartProgress()
{
//do progression here
//and set Progress bar
}
In second page send the message:
private void Onpress(s, e)
{
MessagingCenter.Send(this, "StartProgress");
Navigation.PopToRootAsync();
}
You can find documentation in here.