Did you try the mendix native mobile offering? it is made for these exact purposes. Check this doc page: https://docs.mendix.com/refguide/mobile/building-efficient-mobile-apps/offlinefirst-data/synchronization/
You can use the offline PWA and create a PWA wrapper for it so your offline data is kept in your app container. Offline PWA apps that run in the device web browser may leak their data
As long as you don't have to integrate with Bluetooth LE, like scan for sensors, the PWA offering is probably sufficient. This allows you to develop your app entirely with web technology and no need for separate native mobile page and the knowledge/experience required for that.
You can distribute your app to the stores or enterprise delivery systems by using the PWA wrapper to create a real device app
https://docs.mendix.com/refguide/mobile/introduction-to-mobile-technologies/progressive-web-app/
https://docs.mendix.com/refguide/mobile/distributing-mobile-apps/pwa-wrapper/