Lightroom Mobile catalog export

Planning a trip with DSLR and Lightroom Mobile on Samsung tablet for filing, cataloguing and basic edits.
I have done this previously with a laptop where at the end of the trip I can export the catalog to an external drive and then import into my master catalog on the desktop PC.
How do I do this with Lightroom Mobile ?

I know I can sync with the cloud (but never done it) and won't always have an internet connection. It is expected to be several thousand photos.

I think my only option is to copy files to tablet and then copy back to an external drive and run Lightroom Mobile catalog on the external drive, assuming this is possible.