On iOS 17.4, you’ll be able to see that the divider is thicker and obvious. Long-press on the Safari address bar for an illustrative example. See the gap between “Voice Search” and “Move to Tab Group”?
The blog post didn't mention iOS at all. I'm glad to hear that the feature is coming in the future, though it's strange that the blog post didn't mention it, and also strange that they didn't implement it in 17.0 at the same time as desktop.
Probably because iOS 17.4 is in beta and just got released a few days ago.
This is a very odd coincidence, since the Mac change was released way back in September with version 17.0, which the blog post does mention.