Different geostrategic environment, different degree of support/infiltration, different degree of resistance.
As others have written, the overall military seems to have stood down, and I wouldn't be surprised if most of the strikes from the US in the last few months have coincided with significant backroom contacts to tell the local military to stand down.
Russia and China of course were not in any particular position to ship meaningful weapons to Venezuela -- given the state of Venezuela's military, nation-state economics, and overall governing competence, it would've taken some 3-5 years to establish a military force capable of really resisting US military force outright, and that would require Russia or China actually bankrolling the effort in one which would ultimately fail. And that would assume the US did not simply interdict shipping of cargo ships delivering weapons as well, which neither Russia or China would be willing to escalate with military force to ensure safe passage for.
There would be no particular parallels between the prospect of a similar PLA operation, in the sense that it would not occur in an opening phase manner. At most it might occur after weeks of bombardment in which it would require substantial elements ROC leadership (military and civil) to betray and give up on whoever the figurehead of independence is, and then possibly some sort of high effort coordinated SOF in and out operation against a mostly depleted and uncoordinated ROC military in the same way that the Venezuelan military is now (though the latter's depletion occurred over years and years of neglect).
