A Star Wars short story gives Chewbacca a heroic nickname that emphasizes the impact he has had on the galaxy. Although he eventually became a belatedly-decorated hero of the Rebellion by receiving Han's medal, Chewbacca's recent life leading up to the events of the original trilogy was spent smuggling spice with Han Solo. However, both had defining moments of heroism even in the earliest, most ignominious stages of their careers.
Chewbacca's first encounter with Han is documented in Solo: A Star Wars Story, when the two meet in an Imperial holding pen on Mimban. After some contentious misunderstandings, each one helps the other to escape from captivity, beginning their shared life on the run. Later, when their journey brings them to Kessel, Chewbacca opts to free Wookiee slaves from the spice mines at great personal risk, a choice that he would seemingly make a habit.
In "Tooth and Claw," a story within From a Certain Point of View: The Empire Strikes Back, the bounty hunter Bossk mentions knowing Chewbacca by the name of "Chainbreaker," as he has gained a reputation for freeing enslaved Wookiees in his travels. It is worth noting that Bossk is a Trandoshan, and there is generally no love lost between the Trandoshans and the Wookiees, in particular because the former often hunted and captured the latter for the privateering benefit of the Empire. As such, Bossk's perception of Chewbacca might be skewed toward his actions as a liberator.
The great plight of the Wookiees began after the conclusion of the Clone Wars, when the Pacification of Kashyyyk (in which Bossk had a hand) subjugated their planet. The Empire subsequently adopted the official stance that Wookiees were non-sentient, leading to their frequent mistreatment. Chewbacca's own time in the pit on Mimban is the clearest filmic example of this, but it reflects the state of the galaxy more broadly. It was only in the New Republic era that, thanks in part to Chewbacca's efforts, the lot of the Wookiees began to improve and they were able to properly retake Kashyyyk.
Despite being iconic and much-loved, Chewbacca has always been a bit of a supporting character, specifically serving as something of a sidekick to Han Solo. But this new, altruistic nickname positions him as an interesting foil to Solo, who made clear in his first appearance that he was supposedly uninterested in anything beyond profit. It even shows him in a positive light when compared to other, more obviously heroic characters in the series (for instance, Qui-Gon Jinn, whose disengaged response to the slaving on Tatooine has engendered some controversy). Beyond enhancing his notoriety, Chewbacca's reputation as the "Chainbreaker" shows his true power as a force for good in the Star Wars galaxy.