Well, it's quite possible. Fanfiction allows for different takes on their adventures and personalities. It gives a new perspective that might be fascinating to them, so they could love it.
There could be characters like Hera Syndulla. She is often associated with Kanan and might play an important role in the graphic novel. Maybe Ezra Bridger could also be in it as he has a connection to Kanan in the Star Wars lore.
Whether the Kanan comics are canon is a matter of debate. Some aspects might align perfectly with established lore, but there could be elements that don't quite fit. It's not a straightforward yes or no answer.
Mari can make the story interesting by adding unexpected twists. For example, a character that seems friendly at first turns out to be a villain later. This keeps the audience on their toes.