Regarding the attack roll...does it mean any attack roll for the turn (even a re-rolled one), or is it the finalized attack roll?

THE 3RD VIRTUE OF LIFE: TENACITY: Flurry. Once per turn, when Tigra's attack roll has a 3, after resolutions friendly characters can use Charge and Blades/Claws/Fangs this turn.

It doesn’t say final attack roll so…

Always best just to post the figure in discussion

I'm a firm believer in "Play the figure as they obviously intended." It doesn't say "final" attack roll, but that is clearly what they meant. It is Flurry. You reroll even one of the two attacks and you are basically guaranteed a three on one of the six dice.

If it were clearly what they meant then other figures should have no mention of the word final attack roll, or finalized. Since those terms do appear in the game but not on this example designer intent on your behalf is shaky at best.