Also I believe, using the bridge for using existing ROS1 bags does work (to a realistic degree) as such an interim.
I can entirely second this. We are piping through the ros1_bridge (used in ros1_bridge/src/parameter_bridge.cpp at master · ros2/ros1_bridge · GitHub mode, ROS2 => ROS1 direction) ~10MB/s of data and don’t have any problem neither with latency nor with throughput.