Agree it was a slower part of the first arc, but I don’t think they’re filler. They’re a microcosm of the current issue with a disunited rebellion. With that in mind, they’re likely going to play a part in convincing our other players that it’s time to come out of the shadows and take the risk of becoming a single fighting force; you could already see how frustrated Andor was with Luthen to have to deal with them at all.

To your other point, I won’t be surprised at all if they end up as Dedra’s reliable rebels (good thought… it hadn’t occurred to me), but they could just as as easily be dead by this time next week, as I guess we’re getting something of a time jump between each arc. In either event I don’t think “tangential to the overall progress of the Galactic Civil War” is narratively the same thing as “filler.”