Though, in Prodigy, Admiral Janeway is on the hunt for Captain Chakotay, there are plenty of other options available to her in a live-action movie. Where would she be in Starfleet now? Could she be sent on a special mission that would require some of her former crew members to join her?
Another possibility would be to promote her to Fleet Admiral which would give her much more responsibility and options. The movie could have her struggle with the decision to accept the promotion and what it means to her friends and current colleagues. Following her acceptance, the Federation could be under attack, as it usually is, and Janeway has to lead a no-holds-barred defense against a massive infiltration, much like what happened on Star Trek: Picard but with a new villain more dangerous than anything Starfleet has ever seen before.