How to host multiple different SPA's on a static web app with a web.config file?

I have a general static web app (SPA), and inside it, multiple folders representing more static web apps (SPA). The folder structure looks like this basically

index.html
main.js
main.css
App1/
    index.html
    main.js
    main.css
App2/
    index.html
    main.js
    main.css

In node.js, I have a server file which supports SPA from the root, or from each App folder, using this

import express from 'express';
import * as http from 'http';
import path, { dirname } from 'path';
import { fileURLToPath } from 'url';

const __dirname = dirname(fileURLToPath(import.meta.url));

const app = express();
const httpServer = http.createServer(app);
app.use(express.static(path.join(__dirname, 'public')));

httpServer.listen(process.env.PORT || 3001, function () {
    const address = httpServer.address();
    if (typeof address === 'string') {
        console.log('Sample Web App started at http://%s', address);
    } else {
        const host = address?.address;
        const port = address?.port;
        console.log('Sample Web App started at http://%s:%s', host, port);
    }
});

app.get('*', (req, res) => {
    res.sendFile(path.join(__dirname, 'public', path.dirname(req.path), 'index.html'));
});

This part specifically handles the nested apps res.sendFile(path.join(__dirname, 'public', path.dirname(req.path), 'index.html'));.

How this works is, lets say the request URL looks like https://mywebapp/app1/dashboard, then path.dirname(req.path) will convert to /app1 and use that value, so it returns the index.html file from the app1 folder.

The problem now is that I need to convert this node.js code into a IIS web.config file. So far I have this

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <system.webServer>
    <rewrite>
      <rules>
        <rule name="SPA" stopProcessing="true">
          <match url="^(?!.*(.js|.css|.png|.jpg|.ico|.svg)).*$" />
          <conditions logicalGrouping="MatchAll">
          </conditions>
          <action type="Rewrite" url="/"  appendQueryString="true" />
        </rule>
      </rules>
    </rewrite>
  </system.webServer>
</configuration>

But this only supports SPA from the root. It doesn't work with nested folders. How can I do this?

Thanks