This actually answers the key question for me.
+Vigano says that it's morally certain that Jorge is not the pope.
+Vigano says he's not a "sedevacantist".
So how do they define the term "sedevacantist"?
When Bishop Williamson says that +Vigano stopped sort of sedevacantism (but doesn't rule out that +Vigano might go there), he subtly defines what he means (and likely +Vigano means, since they talk often).
+Williamson:
So, for them, the term "sedevacantist" refers to holding that all the V2 papal claimants were not legitimate.
We see also here Bishop Williamson's attitude about sedevacantism, calling it "the conviction of many serious Catholics". Hardly characterizing it as some "danger to souls" that must be avoided at all costs, as Plenus Venter alleged the Resistance holds. Of course, we also have a CI member who posted some correspondence with Father Chazal, where Father Chazal also holds that Bergoglio is not a true pope.
As for the "official declaration" part, I think almost every sedevacantist and certainly every sedeprivationist would absolutely agree with that, so that does not distinguish them from sedevacantists.
+Williamson also hints at the MAJOR of "sedevacantism", as I've laid it out before.
But, Your Excellency, Archbishop Lefebvre answered this question quite clearly:
Archbishop Lefebvre only hesitated on account of the MINOR, and the certainty with which he could explain how this destruction could have happened.
https://cdn.restorethe54.com/media/pdf/1917-code-of-canon-law-english.pdfFr. Chazal's "sede-impoundism" closely follows 1917 Canon Law. He believes that Bergoglio was lawfully elected and is a public, manifest heretic. Because of his public heresy, Bergoglio has been
ipso facto legally "removed" from office (Canon 188.4) and
ipso facto excommunicated (Canon 2314.1).
The flip-side of the "removal" from office is that the office is
legally "vacant." Even though Bergoglio still acts like he's the Pope, he is in a state of
illegitimacy until he repents of his heresy. In a state of illegitimacy, Catholics must not submit to ANY of his laws or dictates. Catholics must refuse to treat him as an acting Pope. At best he is a
suspended/impounded Pope, while in the state of illegitimacy (Canons 2259-2265).
The
ipso facto excommunication is the first stage of the excommunication process, which is outlined in Canon 2314. The details of the "privations" at the
ipso facto level of excommunication can be read in Canons 2259-2265). According to Canon 2262, which supports the
non-una-cuм position, he is "not able to participate...in the public prayers of the Church." According to Canon 2263, he is "removed from legitimate ecclesiastical acts." According to Canon 2264, his "acts of jurisdiction...are illicit." According to Canon 2264, he is "prohibited from the right of electing, presenting, or appointing." In other words, he is bereft of the normal powers that a Catholic considers a Pope to have.
But because his excommunication status has not been "declared" by a competent authority (level 2), he still retains the fruits of his office
(salary, housing, etc.). And most importantly, he does not lose "the office itself" until he has been condemned/banned/degraded by a competent authority (Canons 2266 and 2314).
So, 1917 Canon Law explains the process and what happens at each stage of excommunication for a heretic Pope. But for all practical purposes, an
ipso facto public heretic is suspended/impounded and the See is
provisionally "vacant" at the moment he becomes a manifest public heretic. Normal Catholics must treat him as a non-Pope until he repents.
Vigano's position seems to be different from Chazal's. On the one hand, he says Bergoglio never took office because of Bergoglio's "defect of consent." But, on the other hand, he says Bergoglio must be "officially declared" a non-Pope by a competent authority. Vigano's position is idiosyncratic and doesn't have a clear basis in Canons dealing with holders of ecclesiastical office. He says he came up his idea ("the defect of consent") when considering the impediments to the Sacrament of Marriage. Like Chazal, Vigano holds that Bergoglio must be treated
as if he is a non-Pope by all Catholics, while waiting for the final judgment of the Church to formally depose him. But, Vigano goes farther than Chazal, calling Bergoglio a "usurper" of the Papacy.
P.S. Bergoglio is a special case. He was never lawfully-elected Pope to begin with. If interested, you can read why at www.antipope.com.