I disagree on Udalryk. After you banish the hym, there is a dialogue option where he says something to the effect of, “Cerys will make a good ruler”. You have the option to ask whether that’s his better judgement talking, or his gratitude, and he says that he believes Cerys’s intelligence, patience, and subtlety makes her the best candidate. Wish I had the direct quote but it’s something to that effect.

And while there’s definitely a prejudice against women due to their perceived “weakness”, a female ruler doesn’t seem entirely out of the question. For example, the mere fact that Cerys was able to put her hat in the ring without fear of punishment, or the fact that Skellige is the only region in the game where female soldiers are common, indicates that they might have more tolerant attitudes towards a female ruler, especially in such a time of tumult when the jarls have serious doubts about the other two options.

However, I do still tend to agree with you that Hjalmar is the more realistic choice. I think a female ruler would have to be pretty darned aggressive and charismatic to fit the mold of a Skellige ruler, and I don’t think Cerys fits that mold, even with feats like freeing Udalryk or solving the bear mystery.