Dynamic routing in flet python

Question

I want to build a chat app with flet in python.

For routing I defined a Router class which handles all the routing. But I am not able to figure a way out for implementing dynamic routes such as "/:username".

How can I acheive dynamic routing in flet without introducing a third party dependency?

router.py

import flet as ft

from routes.login import LoginPage
from routes.register import RegisterPage
from routes.home import HomePage
from routes.user_profile import UserProfilePage

class Router:
    def __init__(self, page: ft.Page):
        self.page = page
        self.routes = {
            "/login": LoginPage(page),
            "/register": RegisterPage(page),
            "/": HomePage(page),
            "/:username": UserProfilePage(page)
        }
        self.body = ft.Container(
            content=self.routes["/login"]
        )

    def change_route(self, event: ft.RouteChangeEvent):
        self.body.content = self.routes[event.route]
        self.body.content.init_page()
        self.page.update()