I am unconvinced that the master manipulator that is L'Rell has killed off Voq. She is the only one who knows this technique and the only one who actually knows what she did. I think it far more likely that she has suppressed Voq temporarily whilst reinforcing the commands that will bring him out again that didn't quite work before. I think he is still in there and the death roar was subterfuge.
Here is my review/reflection on episode one of Picard and also a little bit about why I love TNG so much. Let me know your thoughts on the series so far and your hopes for the rest of the season. https://www.claytemplemedia.com/post/star-trek-picard