UI fails to load offline

I’m new to Ionic and working on upgrading an Ionic3 browser app to a Ionic4.

Everything looks good except for offline operation. All the data used inside application is loaded to IndexedDB at the beginning and ready to be used offline.
But, Ionic4 build process (ionic build --prod) creates 150+ js chunks which are loaded ondemand when user navigates through the application. So, when offline, UI fails to update or updates partially.

Has anyone faced the same issue? Appreciate if anyone can share some ideas to overcome this issue.

PS: I tried to load all js chunks using Angular PWA service worker. (@angular/pwa, @angular/service-worker) and it solved the issue. But seems like, service workers are not yet supported in Chrome on IOS (12.2), which is one of the platforms my app needs to support.
I can add all js chunks in <script> tags to index.html manually, which works too. But keeping that as my last resort.
So, looking for good alternatives.

@angular/core”: “^7.2.11”
@ionic/angular”: “^4.2.0”,
@ionic/core”: “^4.2.0”,