Now Alcimus has been struck dumb - Deo Gratias!!!
As for the last Pope, Peter the Roman, he is to be a true pope appointed by Sts. Peter and Paul the source cited in your post has it ABSOLUTELY WRONG!!!
In as much as that is another distinct possibility, you are correct. Even though I am not totally "sold" on that one, I cannot discount it as a possibility.
I will say that I forgot to include it......as I just plain forgot about it! All theories need to be considered - whether they are popular or not. That is the essense of intellectual inquiry.