In this code:

The httpx library is used for making HTTP/2 requests. The http_version="HTTP/2" argument enables HTTP/2 support.
The download_file() function is modified to use httpx.stream() for streaming the response content over an HTTP/2 connection.
CDN usage is implicit in the URLs provided. CDNs are commonly used to serve static content like files, so if the URLs point to CDN-hosted resources, the downloads will benefit from CDN acceleration automatically.
Threading is used for concurrent downloads, with each file downloading in a separate thread to maximize download speed.
This code will significantly enhance the app's download speed and provide a smoother user experience by leveraging HTTP/2, CDN usage, and concurrent downloading.