It's nice of you to assume this is my first rodeo with Microsoft's subpar software. I've been a forcibly loyal user since the first version of Excel (1985).
First, they already have. They are a large Enterprise client, they've had this software installed for over a month, they do not have the "standard" planner, they have the Project and Planner 3 as confirmed by the IT department who purchased the licenses, installed it, and who manages their Enterprise account.
Second, the promises around how this all integrates with Teams and Office 365 Online is just a sick joke. Anything input in one location doesn't always roll through to the view in Teams (and vice versa).
Third, the way "Planner" has been rolled out is a disaster. None of the documentation matches what you actually see in the software, regardless of what version you have. Finally, this whole "split" between Project and Planner 3 and Project and Planner 5 is just a money grab.
I've already recommended that move back to Monday.com because of how awful this is. We don't have time to waste troubleshooting ALL the things that are wrong with this, we just need it to work.