Fuchsia is a replacement for Cast OS and will begin, or is already rolling out to some of those enrolled in the Preview Program on Nest Hub Max devices.
The Fuchsia OS was released for the smaller Nest Hub about a year back, but most people would have had no idea that the upgrade happened, which is a good thing.
The upgrade is impressive, but the feature set to the end user should be pretty much indistinguishable.
I think the average user would consider it the difference between running Chrome on a Mac or Chrome on a PC, or the swapping of a V6 for a V8 that’s in ECO mode all the time.
Hopefully when your upgrade time comes you’ll notice nothing… absolutely nothing.
Should you want to know how to find out if your device is running Fuchsia, clicky clicky
You can join the preview program in the Google Home app should you want to be a guinea pig.[9to5Google]