Game creator here submitting a reference run for low%. Definitely not optimized, you can surely do better.

AFAIK, you can skip the following unlocks:

• Menu Music
• Menu Graphic
• Menu Particles
• Health (meaning, one hit kills you always)
• Background Art
• Buster Ammo
• Autofire
• Health recharge (not that it does anything anyways since your max health is 2)

Timed via looking at the source frames on the video. Sorry that there's no speedrun timer for this game, I never implemented it =(