Under active development but still at an early stage, last I looked they were solving problems like standardising various configuration APIs file formats etc so a long way it seems from a daily driver let’s say.
However, maybe a year or so ago they started a strategy with Nest where they started rolling out updates which swapped the underlying OS with an early release of Fuchsia on some models and they seem to be expanding that into other models at the moment.
But still very much a thing with meaningful but not particularly public process.