The "Championship Belt" concept comes from boxing/wresting and is the idea that every season, the previous years champion (here the Super Bowl) starts with the belt, and each time they lose they pass the belt to the winning team who becomes the new sole owner.
The concept is explained here:
https://grantland.com/the-triangle/introducing-the-nba-regular-season-championship-belt/
The Pittsburgh Steelers currently hold the championship belt from last year (given they finished last year with the championship belt). See below:
/StopPunting/which-team-will-hold-the-nfl-champi-134c6f1bcbab
Week 0: Steelers
Week 1: Steelers defend against ???
Week 2:
Week 3:
Week 4:
Week 5:
Week 6:
Week 7:
Week 8:
Week 9:
Week 10:
Week 11:
Week 12:
Week 13:
Week 14:
Week 15:
Week 16:
Week 17:
Week 18:
This market closes at the conclusion of the regular season, resolving simply with the team who holds the belt after Week 18. I'll update each week with the current owner of the belt. As a fun edge case, a tie would resolve in a division into two different belts (and could resolve for multiple teams). It's very possible this belt could collapse into the same teams as the new 2024 belt (but it wouldn't change how this resolves.
Also See:
/StopPunting/who-will-hold-the-2024-nfl-champion
/StopPunting/will-the-2023-and-2024-championship
/StopPunting/by-the-start-of-the-203132-nfl-seas