You can modify the endpoint in this script.
But keep in mind that in this case you will lose the ability to update the asset.

I would do it differently:
I would make a request to your server using OnlineMapsWWW, and then process the response OnlineMapsOpenRouteServiceDirections.GetResults.
As an example, you can use the constructor of the OnlineMapsOpenRouteServiceDirections class.

I want to use my own server for both OpenStreet maps and OpenRouteService.
I have seen in the plugin that you can easily put the url for OpenStreetMap, but I don't see the same option for OpenRouteService.
It's possible? How would it be integrated into the plugin?

The only thing I have seen is the OnlineMapsOpenRouteServiceDirections.cs file with the endpoint variable. Would it be enough to modify the url here?

Thank you