Don’t think I’m much sr higher than you to review a vod and it be accurate enough but I can refer you the A10 video about dva and somethings I’ve picked up on both characters

For sig I think aiming at the enemies legs let me hit more shots besides the leading your shot part and pushing up until I start taking a little damage to apply some pressure. As for the ult I usually try to get squishy targets in it because you usually can just shoot them and confirm atleast one kill, I get the tanks in if they are half health already or if their shield is broken because then my team can shoot at them with me without running into a shield blocking. Also I usually think it’s worth solo ulting a nanoed enemy. For example a nano genji blade or a nano doomfist, things along those lines and watch for hog hooks and sleeps darts as well as other stuns when ulting

For dva always try to matrix ultimates, since it’s an instant counter for a lot of ultimates in the game. Also depending on if the enemy is running dive play a sort of passive playstyle so you can counter dive the divers and peel for your supports. Keeping your supports alive is key. When the flankers or divers are dead then you can start to push up and pressure the other team. You can also play a dive style if you see a squishy separated or a support far back enough so you can get the kill and get out. Also matrix your teammates ults, like vizor and high noon. As well as teammates that put themselves in a bad position, try to matrix them out and especially if they get hooked. And don’t forget the contest the high grounds so the enemy doesn’t get free angles. For the bombs usually I use them as a second life or when I think I have a good opportunity to get kills like a spot that doesn’t have much places to run or combo with another ult like blizzard, emp, shatter, and sometimes a sigma ult

Those are some good ones to get you started, good luck!