It matters hugely. If Fuchsia is a research project, then I'd keep an eye on it for engineering inspiration. But if Google's leaders plan to promote it as a serious replacement for Chrome and Android, then businesses might want to invest in Fuchsia app development.
I think the strategy is to make Flutter an attractive tool to build mobile apps across Android, iOS and Fuchsia (it already runs on all three today). Even in an alpha stage, it is a really productive framework for mobile development.
So if Flutter hits 1.0 or beta sometime next year, you would have a way to develop mobile apps for today's platform which will require a smaller investment to run on an eventual Fuchsia platform.
More specifically Fuchsia driver development. That's where it substantially differs, e.g. video drivers run in user space rather than being kernel modules.
For Chrome and Android apps, that's just a bunch of user space APIs/ABIs so it doesn't really matter what the kernel is if the abstraction has been really rigorous from the outset (in Chrome and Android).