Not really, though vendors of Android can provide alternative web views (of course). Samsung used to (may still) which was a giant pain in the ass, since you'd see different behavior out of web views on Samsung versus almost any other Android device, but Samsung was too common to ignore, so if you did cross-platform apps that included web views you ended up with platform specific bugs for iOS, then for two flavors of web view on Android—and then multiply that by the many versions of Android you'd have to support, for Samsung and everyone else, versus maybe 2 versions for iOS for non-super-huge-userbase applications (where those sub-1% users not on the two most recent versions are worth spending money to support, because you have so many users that 0.5% or whatever is still a ton of people)

If anyone could provide web views they'd be practically useless, as they'd just be a constant source of bugs, and everyone would simply start embedding a browser engine instead.

The situation I’m responding to is the suggestion that you bundle your own browser rather than using one provided by Android System WebView or equivalent.

Yes, Firefox can act as a WebView implementation on any Android phone. Apps don't need to ship this.