Right now there are 2 championship belts, owned by the Steelers and Chiefs
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/
Starting with the 2023 NFL Season there will be one belt introduced a season based on the previous years winner. The belt is carried over to the next year at the end of the regular season unless it collapses into a future year's belt (if both belts are owned by the same team). If that happens it would no longer be a unique belt.
Note that a fun edge case happens if a championship belt match happens to tie, in which case two separate belts (for each team) would exist going forward.
History of the Belts
2023:
/StopPunting/which-team-will-hold-the-nfl-champi-134c6f1bcbab
2024:
/StopPunting/who-will-hold-the-202324-last-year
/StopPunting/who-will-hold-the-2024-nfl-champion
This market at latest (there is only one belt introduced a year, so we could know the maximum earlier) closes at the conclusion of the 2030 regular season, with the new belt known for the 2031 season counting.
Also See:
/StopPunting/will-the-2023-and-2024-championship