Is it possible to add some custom entities on the disconnected mobile apps?

Thanks so much Richard for your quick reply, and sorry for the delay from my end to acknowledge it!

It does help to be able to add screens and views to the Mobile apps, let me try that out using the bookshelf reference you have mentioned.

I also had one more follow up question: can we add some custom entities on the disconnected mobile apps?

For the service disconnected mobile application, if a field service rep, who is at the site (with no network) to resolve a service request, and finds an opportunity to do a cross-sell / up-sell / raise a service quote, we wanted to enable two features while in disconnected mode: