There are multiple moves outside the US to address this, but the cost of setting up a refinery is at least USD1b.

Iluka (Aus) has a mineral sands stockpile from their zircon/rutile processing, and are constructing a refinery next to the heap to process the rare earth minerals. Plant is fully funded and should come online end of 2026.

https://www.iluka.com/products-markets/rare-earth-products/

Lynas (Aus) has two refineries (and one planned in the US with DoD funding) and is partnering with a Korean firm in magnet production. They are also the only commercial-scale producer of Dy/Tb outside of China and recently raised an additional AUD800m to fund expansion.