You queried the economics.
Those involved are making bank on some 800 million tonnes of iron ore sales per annum shipped to China and hold leases on significant (as a percentage of global supply) Lithium deposits and Australian land in the millions of acres (a lot of sunlight).
They understand industry at scale, the use of automation to deliver volume, the draw of large economies to sunlight abundant areas for processing and refining, etc.
Transport is planned via Ammonia (hydrogen + nitrogen) - with an excess of sunlight and rapid improvements in domain of electrolysis making seawater as a basis economical, energy losses due to conversion can still be covered to turn a profit delivering bulk ammonia for fertilizer, power generation, and other applications to Europe.
FFI (offshoot of FMI (Fortescue Metals)) has a handwaving set of web pages:
https://ffi.com.au/technology/green-hydrogen/
and have lodged more detailed tech reports for their shareholders via the Sydney, London, and Canadian Exchanges (IIRC).