What actually happens on Android is that you often end up with multiple versions of WebView present: one that's in the immutable firmware image, others that are installed by Google Play, and applications can and often do bundle their own specific version of it or even their own web view implementations altogether (see: Meta and others).
Apple's approach may be slower, but for better or worse, by having WebKit only in the system image and preferring atomic updates, they have pretty much avoided this uncertainty thus far.
I believe the one in the firmware isn't used if it gets updates from the Play Store. So you have that up-to-date version - which most apps use - and you have apps that use their own, which can be a problem, but for example, someone with Android 9 (2018) is still using the latest, fully supported Meta/Facebook app.
Apple's approach is fine as long the phone is receives the latest iOS version. Sure, maybe it's a bit more annoying as you have to do a system update and have some downtime just to update the browser or the gallery app, but it works.
The problem is when the iPhone no longer receives new major versions and you're stuck with the WebKit version that iOS version shipped with. Android is "messy", but a phone running Android 8 (2017) still runs the latest WebView and can also install something like Chrome or Firefox (which still supports Android 5.0 from 2014). And it's a similar story with other apps, like the gallery, maps, messages, etc.
I think Apple understands the benefits of detaching apps from the system. They've started doing that with Safari on macOS a while ago. This morning Safari was updated to 18.0.1 on my Macbook Pro without a system update.
Anyway, my point is that Apple updates WebKit and it counts as iOS still being updated +10 years after the phone release. We don't do that with Android, Windows, Linux, etc.
It's likely that the Pixel 9 (released in 2024 and with 7 years of major Android updates) will be running the latest WebView/Chrome in 2035/36, but because the phone last asked to be rebooted in 2031, no one's going to say "look at Google supporting the Pixel 9 for 13 years!".