I think it just looks for the files on the specific location, and if they're there, it'll happily use it. I think you can download it on a connected device, or VM, and then copy them over, or maybe create your own with tools such as this: https://learnosm.org/en/osm-data/geofabrik-and-hot-export/

I would assume "offline" means exactly that, except of course, you will have to enable GPS.

The apk is ~60 MB on f-droid, so would assume does not include underlying map files. Asking if possible to load them without network access.

i think with earlier versions of android you could get the files in the 'android/data' folder. im using android 11 now so there is no access anymore, unless someone adds an option to store that data in the 'main storage' folder