We are far beyond the GDP vs. GDP(PPP) that started this.
No, you started talking about PPP in response to a news story that described the United States and China competing over influence over the Venezuelan economy: Chinese aid and investment in response to United States sanctions. Those are essentially going to be dollar denominated, and PPP doesn't matter. I've been saying from the beginning that you were wrong to bring PPP into the discussion, because this discussion, in this thread, isn't about domestic consumption in either China or the U.S.
The US's main problem is it's lack of industrial production.
Again, when talking about the effects of sanctions and foreign aid and investment, we should be talking about transactions that occur in the currency at issue. If China wants to provide aid to Venezuela in RMB, Venezuela will either need to spend that on Chinese producers or exchange for another currency to spend elsewhere (including Venezuelan Bolivars being spent domestically). If there's going to be a currency exchange, then PPP of the aid providing nation doesn't matter. A million USD from China is worth the exact same amount as a million USD from the U.S.
On the world stage, as an economic power, the US is losing to China.
I think if we're talking about on the world stage, as an economic power, the interconnected West is best understood as a power bloc. U.S. inconsistency and unpredictability on things like Russian sanctions actually show the limits of U.S. unilateral power while still showing the power of the broader Western order. Yes, China and Russia want to provide the world with an alternative multipolar order, and fragmentation of the Western powers may open up opportunities for that vision, but that competition is playing out along alliances, not isolated nations. In any event, PPP doesn't have anything to do with that particular competition.