b) Israel agreed to the extraordinary term of sharing their data with Pfizer, in exchange for getting doses early, something Canada almost surely won't be willing to do
c) The Israeli PM Netanyahu was facing significant electoral challenges and desperately needed a win, so there was a lot of political will
There's just a lot of willingness to go for "good enough" solutions in emergency situations, and forget the rules for the duration.
Civil defense culture also helps, in that it's trained people to reason about countermeasures that are not 100% ("hermetic" in the local lingo) - you still get in the stairwell to protect from shrapnel, even if a direct hit will kill you anyway. People don't have the gut reaction of betrayal when a 90% countermeasure fails sometimes.
Bibi's career at this point was up against a wall, and he was willing to do anything to 'be first'. Israel has a cagey foreign policy apparatus, I have no doubt they went 'all in' on this, calling in favours, applying pressure in addition to the regular negotiations.