I wouldn't believe it, but with this supposed rumor going around, and this article I just found yesterday on their website: https://sspx.org/en/news-events/news/we-owe-pius-xii-important-clarifications-nature-episcopate it makes me wonder. What I don't like about that article is how they justify the possibility for the first 4 bishops to be validly consecrated, but they don't explain how they ever got the authority to ordain priests seeing how they were not approved by the pope, or at least the article never mentions the pope approving them and giving them jurisdiction.