Currently, there is no way to import existing OpenScenario files into MATLAB without using RoadRunner.
As a workaround, I recommend using ".mat" files to edit scenarios, and then exporting them to the "OpenSCENARIO" format using the Driving Scenario Designer app, which also supports editing scenario files through a MATLAB script.
You can launch the app by entering the following command in MATLAB:
Please note that the Driving Scenario Designer app requires the Automated Driving Toolbox to be installed.
With the Driving Scenario Designer, you can create and edit scenarios, which are saved as ".mat" files. These scenarios can be imported and exported directly within the app.
In addition to using the Driving Scenario Designer app, you can also edit these scenarios with a MATLAB script. To generate a script for an existing scenario on the canvas, click Export > MATLAB Function.
Once you have finished editing a scenario, you can export it as an "ASAM OpenScenario" file by clicking the export button.
For more information about the Driving Scenario Designer app, please refer to the following documentation:
I hope this helps, thanks!