They want to throw this OS on smart home/automative/IoT type things. Android works in these situations, but it’s not necessarily ideal. Thing was designed for phones. It’s likely the only phone firmware in history that’s also been put in cars, espresso makers, washer/dryers, microwaves, and TV’s.
I completely get why the first waves of smart devices tended to just use Android – it’s easy to develop on and “lightweight enough” that the tradeoffs involved were generally acceptable. But those qualities only take you so far. Companies moving on to develop their own in-house OS’s for all these devices was the obvious next step.