> I wonder how domestic the full supply chain is.

The supply chain necessarily includes some Japanese and Dutch companies for their specialized tooling that cannot be sourced from American companies. Many of the spare parts and raw materials can be sourced domestically.

However, it is ultimately unavoidable that many of the constituents within these spare parts, repair kits and raw materials would be manufactured/synthesized in China.

(I worked on the supply chain systems and processes at Samsung Austin Semiconductor for almost a decade.)