So, every time Apple updates WebKit your app breaks. We've gone through this in the past. There are multiple reasons Electron is a win.
1. It's cross platform
Don't have to deal with the fact that Safari is missing these 12 APIs or has different edge cases
2. It's stable after shipping
Users get a new version only when you ship. If you use the native widget then users get a new (often broken) version on every update by a 3rd party (Apple/MS/Google). Example: chrome just deprecated autoplay. If that bubbled into apps your app just broke. Electron could do the same but if you're testing like a good dev that break wouldn't make it to users. You as a dev would find it locally, deal with it, and only after ship to users.
so, no personally I don't want a shared widget. that sounds like going back to DLL hell or worse, just broken stuff.
Doesn’t stable after shipping also mean that if a critical vulnerability is found in the version of electron/chromium that you’ve bundled, the user is vulnerable until you are able to issue a fix? What if the app itself is no longer updated?
Native apps can benefit from using shared libraries, which can be updated in such case. Using WKWebView ensures that vulnerabilities are patched as part of OS updates.
On OSes with sane package managers (e.g. Linux distributions) native apps can share all dependencies, so there is no need to recompile/redistribute each application using affected library.
Sadly, there is no such thing on MacOS (excluding brew/port) and Windows (or even iOS/Android), and even native Linux applications are moving towards bundling all dependencies in a single package.
Typically a native application will depend on shared libraries (or runtime such as jvm, .net) which can be updated independently of the application itself. That said, if the vulnerability is in the application code, you are correct, there would be little difference.
If you use the "API's": standard HTML and standard JS, like a good citizen, I really doubt that would be a problem. And if it is, it's you job to update you app, also Apple provides pre-release versions with good antecedence.
What is the point in that now? It is going to be a similar size as Chromium. You might as well just use Electron.
As a matter of fact, Chromium's/Chrome's engine Blink was forked off from WebKit back in 2013. Current WebKit is Apple's not-quite-as-well-updated version of the engine in old Chrome.
1. It's cross platform
2. It's stable after shipping so, no personally I don't want a shared widget. that sounds like going back to DLL hell or worse, just broken stuff.