Deep Space Rust: I Upgraded a Star Destroyer by Picking up Trash

The near future (about the middle of the 22nd century). The resources of the solar system are exhausted, and humans rely on the "Stargate Network" to colonize and expand to the edges of the galaxy, forming a loose but hierarchical "Pan-Solar System Federation" (referred to as the "Pan-Union"). Interstellar navigation has become popular, but the technology is monopolized by large chaebols and the military, and the people at the bottom are struggling to survive.