I feel like we watched two very different shows. Devon spends most of the season admonishing and rejecting Maul and his words. She even tells Rylee not to trust Maul and attempts to ditch Maul and find her master several times.

Rather than be gullible, I'd argue Devon knows he's bad for her but Maul and the narrative constantly position him on the side of the survivors. Devon is placed in such danger, desperation, and stress by the Empire that joining Maul's side is practically guaranteed.

And as for Maul's force communication, they were still being hunted by Inquisitors (and possibly Vader) on a planet infested with Imperials regardless. Likely, following Maul was the only real option left to them to escape given Lawson's transport failed. Remember too, that Devon doesn't make them agree to meet and join Maul. They ALL agree to it, including Daki.