Boba Fett has never truly been a Mandalorian in the canon continuity and The Book of Boba Fett season 1 finale proves that he likely never will. Boba Fett and his father, Jango Fett, were not only Mandalorians in the Star Wars Legends universe, but they were both the Mand’alor in their lifetimes. In canon, only Jango Fett was a Mandalorian, and while Boba Fett reveres his late father, it only seems to be for him as an individual and not the Mandalorian culture he was part of.
In Legends, Jango Fett’s Mandalorian origin was well-documented in material like Jango Fett: Open Seasons and Star Wars: Bounty Hunter, and while his status as a true Mandalorian was in question for a time in canon, The Mandalorian season 2 established that the broad strokes of his Legends-era backstory are part of the new continuity. The Legends-era Boba Fett was raised as a Mandalorian by Jango, becoming a Journeyman Protector as a young man and leading all Mandalore clans as Mand’alor in his older age after retiring from his bounty hunter profession.
Canon’s Boba Fett was, strangely, never raised as a Mandalorian by Jango Fett, despite his many lessons in the bounty hunting field. As a result, Boba Fett doesn’t claim loyalty to any Mandalorian subculture, nor does he bother correcting Death Watch members in The Mandalorian season 2. In The Book of Boba Fett episode 7, “In the Name of Honor,” Boba Fett offers Din Djarin, a member of the Mandalorian Children of the Watch, a chance to escape a seemingly hopeless battle, which Djarin refuses, citing his Mandalorian code of honor. Fett dismisses the Mandalorian creed but nevertheless fights alongside his friend. Fett’s lack of respect for the Mandalorian way proves that he’ll remain an independent, albeit honorable, warrior and leader, but not a Mandalorian.
Boba Fett went through great lengths to reacquire his beskar armor in The Mandalorian, and while Fett isn’t a Mandalorian himself, the armor belongs to him, as the son of the late Jango Fett. Boba Fett’s value for the armor doesn’t come from Mandalorian customs, but rather his love for his father and appreciation for the weapons-laden, blaster-proof beskar suit. The armor held sentimental value and was a practical tool in combat.
With the assumption that Jango Fett’s Legends-era backstory is part of canon now, his loyalty to the Mandalorians makes sense, as his family was murdered by the Death Watch terrorist group, but Jaster Mereel’s True Mandalorian faction raised the young Jango. Boba Fett was raised by a Mandalorian, but not within a Mandalorian clan, and therefore most likely didn’t feel any affinity for the culture. Moreover, Boba Fett grew up during a time when the Mandalorians were, at various points, denying their warrior past, divided by a former Sith Lord, or being wiped out by the Galactic Empire.
To Boba Fett, the Mandalorians might have seemed like a doomed bygone culture that would destroy him if he joined them. After Jango Fett’s death, Boba Fett was alone in the galaxy, so turning his back on the Mandalorians may have been a survival tactic, considering their precarious position in the galaxy. Considering Fett’s words at the end of The Book of Boba Fett’s season finale and the possibility of a new age for the Mandalorians under Din Djarin’s rule, however, Fett joining the culture is highly unlikely, but not impossible.