Reality is, the US cannot supply all of their regime change / geopolitical shenanigans operations all at once, mainly due to their MIC not being able to cover how much shit actually gets used (you can look at US actions in Syria for that).
They want to be able to pivot towards China and secure the Middle East while containing Russia, but doing all three at the same time is impossible, which is why they're trying to pressure Iran and Russia into giving up without them actually commiting more than they already are.
China and Russia are more likely already aiding Iran in some extent, but their aid is limited (no vast network of bases and shared equipment with Iran, inferior logistics when compared to the US).
Iran itself shares the blame with this, partly due to its reluctance to trust China and Russia after the arms embargo ended and wanting to strike deals with the US.
As far as i'm aware, Russia is exporting gas to Iran right now, as well as most likely providing satellite intel and helping root out Mossad in the area. China's propping their economy.
It'll get down to "Is the US / Israel able to collapse the Iranian regime and force a change or not", really.