If only for the fact that he was more subtle than Bergoglio, and that he died before a single document of Vatican II was promulgated. Given the transitional period between Pius XII (definitely a true Pope) and Paul VI (definitely not a true Pope), it is only natural that the ostensible pontificate of John XXIII would be more ambiguous. As I said, I’m of the opinion that he **was not** a true Pope; the exact *point* at which that occurred is something I’m less certain of (whether he lost the pontificate due to manifest heresy, or if he was ineligible for election due to being a pertinacious heretic prior to that point, public appearances notwithstanding).
(And to answer your other question, given that John Paul I publicly adhered to Vatican 2 in its entirety - even to the point of remarking that they “must have been wrong” on the question of religious liberty as it was understood prior to V2 - I’m inclined to say no.)
Is there a particular point to your inquisition with regards to my thoughts regarding who was or was not a Pope?
Yes, there is. It seems you're decisive about the legitimacy of some "popes" but indecisive about that of other "popes".
And I'm wondering why and by whose authority you make such decisions.
If, by the hand of God, Bishop Strickland, is elected Pope at the next, hopefully soon, conclave, would you acknowledge his as a true Pope?
Why? Can you explain this to me?