I would think American Rare Earths is the better play versus TMC.
Their holdings include a slug of Wyoming State Acreage that should see expedited permitting versus federal lands (which include offshore seabeds, yes?). If the Supreme Court strikes down most of the Federal agency regulatory authority as expected, this could change. Environmental protections are way too complex for Congress to spell out in passed laws, yet that's what conservative jurists are demanding.
The bottleneck for rare earths is domestic processing capacity. An inherently dirty business. I have not done a deep dive into progress made on this front.
But very exciting news from both a national security and clean tech perspective!
Investment worthy? Hard to say. Speculative for sure...