Why I said that? Because all of their guns that runs on bullets or even lasers looks and moves nearly exactly like the bullets shot by regular-looking guns from thugs(Hero Cinematic) and cops(Roadhog and Junkrat trailer AND comic). Yet, most of them have their own barriers, their dodge tactics and few still take covers when they do not need to. Of course, other specific guns such as the Hellfire shotguns are more powerful than those types of guns.
You ask, how about the other guns from other fictional verses? They show better feats than regular ones. For instance, Dante's gun which shoots a bullet so fast with so little mass, to push his giant Rebellion to make it move fast enoough to cause air friction in DMC3. See where I'm going? Samus is hard for me because I don't play the game. But, if the enemies move faster than light and, in manga or cutscenes, she successfully shoot her canon at them, that means it can move much faster than light.
Depends on her health. Is it like a thousand HP away from Cloud's? Does not matter. If she can survive the supernova as well, she's at whatever supernova level is. If you find the damage sephiroth did to Cloud and compare it to Tifa's HP, it will find you whether she can survive it or not. That is how I find scaling. I am not dodging it. If she really can, get a Youtube account, make a video of you, as Tracer, blowing yourself up with full health, post it on Youtube and show it to us.
If she does survive, congrats. Her durability is unknown since she can also be hurt by one second in the flames of her failed Pulse Bomb, slammed by physical wall level widowmaker and falling off a height to be heavily wounded. If she didn't, I told you so.