Holybro Pixhawk 6X MicroXRCE Interface RTK_GPS correction data using the Agent


my current setup:
I have a RPi 5 running ROS2.
I have the Pixhawk with PX4 communicating using the px4_ros_com package.
I have all the data topics and the PX4 sends all the necessary info we need using the MicroXRCEAgent (transport: serial)

The RPi 5 has an active internet connection.
We use the Ublox Thingstream PointPerfect NTRIP service to get correction data.
The ROS2 package ntrip_client connects and gets the data from the service and publishes it to the topic /rtcm

I am quite not sure how to use the MicroXRCEAgent to send in the correction data we receive from the online service to the PX4.

I see that there is GpsInjectData uROB message type but I do not see a topic on ROS2 /fmu/in/.

Please point me in the right direction to send/feed in the received RTCM messages to PX4?