IETF RFC 8441 (https://www.rfc-editor.org/rfc/rfc8441.html) described a way to bootstrap WebSocket under HTTP/2.
That said, I don't know whether or not people are actually doing it in the wild.
On the client side, both Chrome (https://chromestatus.com/feature/6251293127475200) and Firefox will use it when available, but I have encountered some issues with cross-origin support (https://issues.chromium.org/issues/363015174)
IETF RFC 8441 (https://www.rfc-editor.org/rfc/rfc8441.html) described a way to bootstrap WebSocket under HTTP/2.
That said, I don't know whether or not people are actually doing it in the wild.