Andor will debut in just over a month, and the recent second trailer revealed that Saw Gerrera will be appearing in the show. In Rogue One and the book Rebel Rising, it’s established that Jyn spends a lot of her life with Saw’s Partisans. With the Partisans appearing in Andor, Jyn Erso may also make an appearance in the show.
Jyn spent eight years in the care of Saw Gerrera, going on several missions with him. However, as she explains in a tense moment in Rogue One, Saw abandons her when she was sixteen, leaving her to fend for herself.
The book Catalyst reveals that Jyn was born in 21 BBY, meaning that at the time of Rogue One, she is either 20 or 21. The first season of Andor is set five years before Rogue One, which would mean that it’s set in 5 BBY. This would make Jyn either 15 or 16.
The Partisans are undeniably an important part of the early Rebellion, being one of the first groups to repeatedly resist the Empire. Andor is likely to expand on their role, and dive into their tendency for extremist action, rather than a measured response. In the second trailer for Andor, Luthen is shown to have at least some reservations about Saw’s motivations, hinting at a possible tension.
As Jyn was highly involved with the Partisans throughout her early life, it’s possible that she might show up as part of the group in Andor, depending when in 5 BBY she turns 16. Jyn would likely only have a small cameo role, and wouldn’t play a huge part, as she meets Andor for the first time in Rogue One.
The book Rebel Rising explains that after Saw dumps Jyn, she finds a new home and family, so at that point is very unlikely to appear in Andor. That also rules out an appearance in the second season of the show.
Jyn would make for a fun cameo in Andor, as it would show audiences that other characters in Rogue One are also on the path to rebellion. Such a cameo would also tie Rogue One and this show closer together. However, even though it’s possible, it isn’t guaranteed.