Aren't there different degrees/types of jurisdiction? Didn't the sspx receive ordinary jurisdiction for confessions only? I don't think they received jurisdiction for marriages, which is why they are allowing novus ordo priests to come and "officiate" at weddings. Further, there is also jurisdiction received from the diocesan bishop, which the sspx certainly doesn't have, at each of its chapels, in every country, in all parts of the world. If the pope gave them this already, then they wouldn't need a personal prelature.
I am not knowledgeable enough to know if there are
different degrees/types of jurisdiction, so you may be right.Jurisdictions for marriages are given either:
1.) on a case by case basis as you correctly noted regarding the need for a Novus Ordo Priests to officiate the wedding
2.) or in advance, as some bishops have granted the SSPX jurisdiction for marriages within their dioceses without asking permission for each wedding.