...but who nevertheless still hold the office and jurisdiction (Billuart and the more common opinion of theologians).
I think that there is a strong argument to be made, regarding UPA, that since Francis did not properly accept his election (à la Cassiciacuм Thesis), UPA is impossible, since it requires the consent of the elect*.
Regarding supplied jurisdiction, it seems to me obvious that Christ would supply jurisdiction to say, appoint cardinals, but never for something like the New Mass or Traditionis Custodes. I think it is better to treat Francis as if he were bereft of jurisdiction except for those things strictly necessary for the good of the Church, i.e., appointing electors so that the material aspect of the Church does not die off. This is the end for which Billuart and others conceived of supplied jurisdiction, after all.
* This is the view of the Salmanticenses and others