The Trump administration is entirely transactional. They will not do anything for anyone unless they are getting something back in exchange. However, it is also very performative. Trump cares more about the optics of a deal than the deal itself. How many times have you heard Trump talk about his own or someone else's "ratings"? He's not talking about any objective metric, he is talking about popularity.
So, it entirely makes sense that his aim was to publicly humiliate Zelenskiy and force him into a "deal" with lots of "value" coming back to the US. As long as the press can report a high number in the deal, the terms of the deal are not important. Trump could care less whether the deal was for minerals, or anything else. He cares more about the headlines that the deal would bring then the terms of the deal itself.
And since it's quite likely that he is aligned wih Russia, making a deal that is difficult to technically deliver on with Ukraine may be purposeful. It would give him cover at some point to complain "Ukraine isn't living up to the terms of this deal", because the terms may be unattainable. However, I don't think Trump thinks that far ahead, he's only concerned with today's headlines. He may be getting coached on that by his Russian friends on how to appease domestic critics while putting Ukraine in a lose-lose situation.