import panel as pn
import time

pn.extension()

placeholder = pn.pane.Placeholder("Hello")
placeholder

placeholder.update(pn.widgets.TextInput(value="Hello again!"))

placeholder.object = "Hello once more!"

placeholder = pn.pane.Placeholder("⏳ Idle", stylesheets=[":host { font-size: 24pt }"])
placeholder

with placeholder:
    placeholder.update("🚀 Starting...")
    time.sleep(1)
    placeholder.update("🏃 Running...")
    time.sleep(1)
    placeholder.update("✅ Complete!")
    time.sleep(1)