Not a broken five color commander like Jodah the Unifier then, but a solid commander for an Ally typal deck - if only the Ally card pool was deep enough to make that viable
Similarly, you can use something like Consider to ditch cards on top you dont want, or Brainstorm to set up the top of your library with lands or spells for your Future Sight effect
Millicent, Restless Revenant fits the bill with its spirit-reliant ability and its token generation, and there are enough spirits in the game that you can tune your deck to your budget and gameplay environment
Rielle decks often focus on card draw payoffs and making the commander into a massive threatit doesnt take much for Rielle to threaten large amounts of damage, especially with access to tricks like Violent Urge and Temur Battle Rage
Since the deck already has a bunch of energy counters being made, Cayth has a ready target for proliferation
It's not bad by any means, but I don't know if I'd pick it over other options