OK ! I finally use as proposed react-router. But I used the Hooks version (with <A>...)

So, the little dashboard is splitted in X parts :

• The HTML with only the minimum and root. <div id="root"></div>
• The CSS (nothing to say more)
• The sub apps in a specific folder "Apps"

import React from "react";
import { A } from "hookrouter";

class Prog1 extends React.Component {
  render() {
    return (
      <div class="contProg1">
        <button class="close">
          {" "}
          <A href="/">Close</A>
        </button>
        <h1>Program 1</h1>
        <h2>Test1</h2>
        <h2>Test2</h2>
        <h2>Test3</h2>
        <ul>
          <li>AAAAA</li>
          <li>BBBBB</li>
          <li>CCCCC</li>
        </ul>
      </div>
    );
  }
}

export default Prog1;

• The router page to switch between apps and main Dash.

import React from "react";
import Prog1 from "./Apps/Prog1";
import Prog2 from "./Apps/Prog2";
import Prog3 from "./Apps/Prog3";
import Prog4 from "./Apps/Prog4";
import Dash from "./App";

const routes = {
  "/": () => <Dash />,
  "/Prog1": () => <Prog1 />,
  "/Prog2": () => <Prog2 />,
  "/Prog3": () => <Prog3 />,
  "/Prog4": () => <Prog4 />
};

export default routes;

• The main page, the Dashboard (App.js).

import React from "react";
import { A } from "hookrouter";

const elements = ["1", "2", "3", "4"];

function Dash() {
  const items = [];

  for (const [index, value] of elements.entries()) {
    items.push(
      <A href={"/Prog" + (index + 1)}>
        <button key={index}>{value}</button>
      </A>
    );
  }

  return (
    <div className="Dash">
      <table>
        <tr>
          <td> {items} </td>
        </tr>
      </table>
    </div>
  );
}

export default Dash;

• And to finish, the Index page :

import React from "react";
import { render } from "react-dom";
import "./styles.css";
import { useRoutes } from "hookrouter";
import routes from "./router";
import NoPageFound from "./Apps/404";

function App() {
  const routeResult = useRoutes(routes);
  return <div className="Dash">{routeResult || <NoPageFound />}</div>;
}

render(<App />, document.getElementById("root"));

It works well. I just need to add something like MemoryRouter or something else to hide the URL and prepare for mobile version. I'm just a little bit scared when I will insert this part in a Django project. Or, maybe I should separate it ? (You don't need to answer, I will close I think).

Thanks :)