The answer is yes according to code and documentation [0]:

> The stream multiplexing capabilities of QUIC allow reducing the head-of-line blocking that SSHv2 encounters when multiplexing several SSH channels over the same TCP connection

....

> Each channel runs over a bidirectional HTTP/3 stream and is attached to a single remote terminal session

[0] https://www.ietf.org/archive/id/draft-michel-remote-terminal...