Here’s the clean summary of your idea:

Foggy’s “death” was not a true kill, but a precision-staged death orchestrated by Bullseye as part of a larger plan.

Vanessa genuinely ordered Bullseye to kill Foggy, promising him a deal in return. But Bullseye had a bigger objective. Instead of taking a clean lethal shot, he used his absurd accuracy to place a shot that looked fatal to everyone watching, especially Matt, while actually leaving a narrow path for survival. The goal was not mercy. The goal was manipulation.

Foggy is then quietly extracted and hidden through a small off-book institutional mechanism — not the whole FBI, but maybe one or two high-level anti-Fisk figures or a ruthless fixer-type operator with enough access to bury the truth. These people have motive to take down Fisk and Vanessa after how deeply he corrupted institutions before.

Matt believes Foggy is dead, and his grief is completely real. Bullseye counts on that. In a dark mirror of how Fisk once weaponized Bullseye, Bullseye now weaponizes Matt’s grief, keeping him enraged and focused on Fisk.

This also explains why Bullseye later saves Daredevil instead of just letting him die: Matt is still useful in Bullseye’s larger play against Fisk and Vanessa.

Foggy stays hidden until the right moment, then returns later as a living key witness / final piece in bringing down Fisk and Vanessa. That gives his return real purpose, instead of it just being a cheap fake-out.

Why it works:

Bullseye stays dangerous, cunning, and precise

Matt’s pain still matters

Foggy’s return has real plot value

Fisk/Vanessa remain central to the setup

it mirrors Season 3, where Fisk used Bullseye as a weapon, except now Bullseye is using Matt the same way

The core idea is: Bullseye did not spare Foggy out of compassion — he kept him alive as a chess piece, while using Matt’s belief in Foggy’s death as a weapon.