Hello, folks, I am coming back here to update you regarding my initial question.
Basically, I had everything I needed to perform the Geolocation with Rugged. In the end, it was just a problem regarding the initial date, and the date from my quaternions and vector position.
As soon as I fixed it, I was able to obtain the rotation in relation to nadir. For that, I made sure to properly load the metadata from my XML files.
As a result, I could geolocate my points over Portugal Continental, as expected. For anybody with the same issue, I recommend following this Rugged example, changing to your use case.