Our QUIC implementation noq is a standards compliant QUIC implementation that in addition to RFC9000 also implements the QUIC multipath draft RFC.
We try very hard not to invent new things unless absolutely necessary. In a few places we had to implement draft RFCs, QUIC multipath and QUIC NAT traversal. And there are some corners where we had to add our own extensions. But we try very hard to keep this to an absolute minimum.