It has been under heavy heavy development for many years now.
The fact that they are now starting to talk about it publicly now is probably a sign that they are looking to move beyond just IoT in the future.
For example, I know it’s coming to Android (not necessarily as a replacement but as a VM) and I know there is some plans around consolidating ChromeOS and Android as well. I expect that is also going to be another place we might see it before too long.
I know they are also working on a full Linux compatibility layer called Starnix [1] as well where I believe the goal is you can just run all your Linux workloads on Fuchsia without any changes is the goal AFAIK so you can probably extrapolate from there that the end state is going to be roughly in line with anywhere Linux runs currently is a good potential fit for Fuchsia and it will come with a lot of additional security guarantees on top of it that is going to make it particularly attractive.
[1] https://fuchsia.dev/fuchsia-src/concepts/components/v2/starn...