This tool can be used to connect to an arbitrary WebTransport server. It has several limitations:
It can only send an entirety of a stream at once. Once the stream is opened, all of the data is immediately sent, and the write side of the steam is closed.
This tool does not listen to server-initiated bidirectional streams.
Stream IDs are different from the one used by QUIC on the wire, as the on-the-wire IDs are not exposed via the Web API.
The WebTransport object can be accessed using the developer console viacurrentTransport.