I think Dodonna would be the least they could do (or Mothma or Bail).
Saw Gerrera might make sense because they sort of created him but if what I’ve heard of his character in RO is correct I don’t know how well he’d fit.
I am starting to wonder how long they see this show going. I always thought of it as a prequel that’d end by the time of ANH but I suppose they could go past that if they really wanted, though I’m not sure if they would.