Vue + Realm = Persistence Data ?

I have developed a project with vue, mongodb and capacitor, however I need to convert my project to offline 1st app on mobile.

My case is i want to make app behave like whatsapp, saving all text and images to folder on the device and sync when online, however realm web sdk was fastest pick but it got limitation of data persistence.

the app is large and would take very long time to remake on like react-native … etc

how could i achieve this ? any direction is appreciated, thanx