I haven’t heard of any efforts to do this, but there isn’t anything stopping it from happening from a technical perspective. ROS 2 is designed so that the middleware layer is able to be changed out to different implementations. There was a recent survey of the community to seek out : alternative implementations for the middleware layer, the conclusion of the study was published recently. This may be a helpful report to see the relative strengths/weaknesses of other transport implementations.
The first steps would be to check out rmw, which contains the headers describing the necessary interfaces a new middleware would have to implement in order to be used as part of ROS 2.
Another valuable thing do do would be to check out the recent work in rmw_zenoh, as you can find many of the potential sticking points of creating a non-DDS-based rmw implementation.