However, I see that it depends on Bi3D and that Bi3D only lists the Orin NX 16GB version in system requirements.
Will I be able to run it on my 8GB version?
Is there any workaround to still use freespace segmentation like using ESS ESS DNN Stereo Disparity | NVIDIA NGC or does freespace segmentation only run with Bi3D.
Is there any isaac ros module then to be able to perform obstacle avoidance // provide occupancy grid to nav2 using ESS?
What would be the best way to proceed knowing that I must use the Orin NX 8GB?
For an optimal result, we suggest using a 16 GB version, but it can also work on your Orin NX 8Gb version. The performance summary for all devices is available on this page Performance Summary — isaac_ros_docs documentation
You can combine the Isaac ROS free space segmentation and Isaac ROS DNN stereo disparity package. If I misunderstood your question, please let me know.
You can use Isaac ROS vslam and Isaac ROS nvblox to perform the obstacle avoidance. Please take a look at this demo with Isaac Sim that perform with Nav2 Isaac Sim Examples — isaac_ros_docs documentation
My suggestion is to start by following our tutorials step by step and learning the capability of each Isaac ROS package. Then, start designing your own ROS 2 launch file, combining the packages you need.
A list of packages that can be interesting for you: