Hello everyone here!
With the great help of @joewong00, now we have tested and fixed the Witmotion protocol decoders from witmotion_ros driver on real Witmotion WTGAHRS1 TTL 10-axis enclosed IMU/Magnetometer/Barometer/Inclinometer/GPS receiver. ROS 1 version is released now for noetic, but the ROS2 release is still WIP. The revealed bug in the decoder routine is fixed, and the GPS processing pipeline is considered from now ready for production.