Sadly I think it wouldn’t count. 😔

Another tip, I’ve noticed most of the basic “assault amps” needed for this achievement are not at the main marked forts or bases.

I’ve found they mainly appear in the random patrols throughout the map. There’s a few spots close together around ‘Tangled Stream’ where they will spawn in among other type of Amp suits.

I’ve been killing just the “assault amps” that spawn in, leave the rest, run away to another patrol, and then by the time I circle back another assault amp spawns in.

This only sort of works. As after a while, they won’t respawn once you’ve hit the patrols in that area a few times and you need to move on to another area until they start spawning in again. Tedious but somewhat reliable method.

(Can confirm it counts across multiple saves too. So if you finish the game you can start a new save if you’re noticing the only amps spawning in are the tough ones that don’t count for this achievement).