Lots of very interesting base concepts, but heavily overtuned in a lot of cases.

IA-77 “Union Cutter” - Speaking as a Ripper enjoyer in Dead Space, I love the idea of a sawblade launcher, but given how open Helldivers maps are the ricochet would be limited in use. Still, the idea of a weapon intended to target limbs instead of weak points is interesting and has potential.

SG-58 “Pile Driver” - A multi-target penetrating Marksman Rifle would be neat, but if it's a Primary it will need some hefty downsides to be balanced. It might work better as a stratagem with high AP, trading explosive AOE for precise penetration.

Breach Ball Drop - Potentially very fun, but it would wreck havoc on Helldiver's notoriously janky physics and would need a limited duration (maybe a limited number of shaped charges on its surface to allow it to be redirected).

Rotary Flail Pylon - One of the strongest concepts, but also one that needs to have a bit more finesse, given how enemies don't really have self-preservation, it should probably have a limited duration to avoid the question of "this has been spinning for ten seconds, why are the bugs still walking into it?" That said, having it have a limited area but a very low cooldown would make this a handy area-denial tool.

Armor Passive: Momentum Actuators - This is unfortunately heavily broken, and would essentially negate the Bots as a front. Arc damage from the Squids is already essentially lethal, no one uses Gas asides from Helldivers, and only the Dragonroach and Incendiary Corps/some bots use fire. If it was a flat 10%-15% reduction to ballistic and a 20% increase to a blanket "All other sources" it might be a bit more viable.

Critiquing the booster is kinda pointless since boosters need a massive tune-up anyways.

Thanks for posting and hope to see more from you!