The deaths of Hawkeye’s family in the beginning of the film are a result of the snap and thus have already been counted in the previous Avengers movie.
19:06 Thanos is beheaded by Thor
54:29 We encounter Hawkeye laying waste to some gangsters. 10 are already down when we arrive and he throws a knife into another and then 2 more.
54:42 He gets another on the stairs then puts another through a window.
54:54 He throws another out a window and when he lands we see at least 2 others he already killed. The third could possibly be the last guy thrown out the window.
55:03 As he fights the boss you see 11 other bodies littered around the street that were killed in the fight.
56:16 He kills the boss.
It is important to note that from here forward there will be kills that likely also happened during other films in the MCU, but due to the alternate timeline theory it is impossible to tell, but we will count them here.
1:07:48 Hulk kills a Chitauri with a car a lot
1:08:18 The ancient one destroys a couple of speeders killing 6 and gets another at 1:08:25
1:13:35 Alternate nebula kills a guy in armor then another
1:13:48 Alternate Gamora gets one
1:53:46 Black Widow dies
2:10:12 Hawkeye kills 4 aliens in the sewer through explosion and swords
2:11:40 Nebula kills alternate Nebula
2:18:59 This is where the main battle sequence occurs.
2:19:00 Thor electrocutes 8
2:19:04 Hulk throws one into a ship as Ant-Man punches down a big ship alien
2:19:11 A Dore stabs one and then a speeder explodes into the ground
2:19:16 Iron Man takes out a speeder and Pepper takes out a large-ish ship (we will count this as 1 since we don’t know capacity). They then take out 2 more speeders back to back
2:19:21 Back with Cap and Thor we see 2 on the ground already as Thor takes out a big guy and Cap gets 2 with Mjilnor, Thor gets another 2, Thor and Cap get 3 more rapidly between them and switch hammers
2:19:30 Rocket shoots 7
2:19:32 Iron Man gets 7 as someone flies by to get 2 others
2:19:40 Ant-Man steps on Supergiant
2:20:06 Korg and Quill team up to get 9
2:20:17 Alternate Gamora saves quill by shooting one
2:21:04 Big alien gets a Dore and 2 other good guys before Falcon kills it
2:21:21 Cap gets one
2:21:57 Dr. Strange gets 6
2:22:34 Thanos gets a sorcerer as Corvus gets an Asgardian
2:22:48 Hawkeye shoots one then Black Panther blasts back 10
2:23:03 Found an inconsistency as Black Panther takes the glove to Ant-Man and the Wasp, who is that giant behind him shoving a ship through a hole… Ant-Man
2:23:06 Black Panther lands and takes out 5
2:23:53 Spider-man takes out 8
2:24:19 Corvus gets one then the orbital bombardment begins as it takes out 3 randoms, a speeder and a large flying alien then another speeder
2:25:01 Spider-Man takes out a couple more
2:26:12 Captain Marvel takes out Sanctuary(There is a wiki that lists the minimum crew complement of this ship as being 1500, but I cannot find where they get their info, so we will unfortunately have to ignore this huge ship blowing up.)
2:27:25 Scarlett Witch gets what looks like about 20 with a blast
2:27:28 Nebula shoots one, then Gamora at least wounds a big one, the Okoye kills Corvus
2:27:42 Pepper gets 2 then Captain Marvel takes out 4 tanks that looked like they had crews of 5 each
2:28:03 Exploding van takes out what looks like 58 randoms
2:30:33 This is where Iron Man snaps and then dies. This is where things can get a little hairy. There are those that would argue that Iron Man kills all the bad guys here, but I would disagree for the following reasons. First, when Thanos does the snap, he explicitly stated he intended to kill off half of the universe’s population. When we see the effects, we see the falling to leaves effect as it encompasses just the life forms and what they are wearing (we even see weapons dropped). In the Iron Man snap, he doesn’t explicitly state anything about what the snap means. Also, while we see a similar effect occur, it not only happens to Thanos and his army, but also to all of the ships and equipment. Those two inconsistencies lead me to believe that Stark with his understanding of how reality works to this point just sent those individuals back to their own point of origin so as to prevent further problems in the timelines.
Here is a kill count that is much higher than ours. It counts the deaths of Hawkeye’s family at the beginning which is understandable. It also gives an arbitrary 1000 kills at the end snap. Even if you argue the snap is indeed killing the army, there are much more than 1000 troops in it. Not sure where they got this number.
This count is closer to ours, though still higher. It makes the same call on the family at the beginning and also counts the snap at the end, but only counts the individuals you can see disappear on screen.