I'm exploring the potential of WebTransport for my web application
How will WebTransport impact the performance and security of web applications compared to traditional HTTP(s) protocols? Are there any loopholes to worry about?
WebTransport holds good compatibility for Chrome, Edge, Firefox and Opera. You can also find differences when it comes to some experimental parameters. Just take a look at this doc.
As to polyfills, a polyfill (or rather ponyfill that provides functionality as a standalone module you can use) called webtransport-ponyfill-websocket that implements some of the features of WebTransport is available. For more information, you can refer to this doc.