I've had my Ultra 2 since launch, and its screen is pristine, not even the slightest damage to it. And I think I've been rougher on it than I ever was with my series watches. I can think of at least three times just in the past week when I've banged it screen-first into something or dragged it across a hard surface. It's far more resistant to scratching than the Series watches.
IMHO the Series watch's Ion-X glass is fine too, unless someone is super hard on it. I went about 3 years between each, and yes there'd be minor micro scratches, maybe a chip or two on the edges, and one had a decent sized gouge that I think came from a door handle, but even that was invisible when the screen was on, you could only see it with the screen off, clean, and at just the right angle. But ultimately this is utilitarian technology with a lifespan of 2-5 years, it's not a generational heirloom or something.