I first heard about the Maverick on jalopnik about 3 or 4 years ago but it wasn't called a Maverick then. There was a lot of discussion about Fords global small truck/ute platform and there was a lot of worry and concern that Ford was going to use it to introduce a watered down version of the Bronco. Fortunately, the development turned out to be the Bronco Sport and the Maverick.
Rest assured this truck has been in the works for a very long time.
Here I went and found the articles, they were from 2018 when the small Bronco Sport and a mysterious small unibody pickup truck began showing up in Ford presentations. If they're showing up in those presentations it's likely that they were working on them at least two years before then.
A guy on Reddit who seems to be very involved in Maverick production mentioned he's been working on the Maverick project for three years so I think Ford has put a lot of effort into this product launch
There is always a lot of planning and preliminary content discussions that go on before a program gets 'approved' which is then considered the official kickoff and people are assigned and real work starts. The Maverick was 3 years from kickoff to release.
Seems like they made a number of smart decisions a few years back. Bring back the ranger as a quick stop gap, Remake the bronco, and come up with the maverick.
Between those decisions, and ditching the car segment, seems like they have made some smart moves!