As the author of 'Bit Map', of course that is what I recommend.
Bit Map is not only a mapping/navigation app, but also a limited GIS. This means that the user interface is not quite as simple as some other apps, but the spatial data management is far more capable than most other apps. (Note that it is only available for Apple devices, including iPhone, iPad and Mac).
It can load up a vast array of online maps (both raster and vector) as well as offline maps (again, both raster and vector), so long as they use supported standard formats. It can download areas of online maps so that they can be used offline.
It does work with NSW "SIX" maps (spatial information exchange maps), including aerial imagery and topographic maps.
It can import and export many, many different spatial data formats, including GPX, GPKG, Shapefile, File Geodatabase, KML, and many more.
It can not only record tracks and waypoints, but also allows you to manually create point, line and polygon features in arbitrary map layers (not that you'll want to do this for bushwalking, I guess).
It is a small one-off up-front cost of $4.49 and does not require any ongoing subscription. Actually, if you buy it on the first of the month, for the next few months, it's COMPLETELY FREE (but don't tell anyone else!). (It's an extra $19.99 for the "Pro" version to manually add features to arbitrary layers but I don't think you'd want that.)
This is insanely good value.
Information about the app is at:
https://nixanz.com/bitmap/Information about the SIX maps URLs that can be configured in Bit Map is at:
https://nixanz.com/bitmap/resources/map-services/User guide:
https://nixanz.com/bitmap/user-guide/App Store:
https://apps.apple.com/au/app/bit-map/id1560781471