In that scenario I’m not sure if Ukraine allies are as significant as Russians allies. I very much doubt China has any tolerance for nuclear eacalation, that sets a precedent that will change how the West behaves in Taiwan. I imagine Xi’s fury at being undermined this way would manifest in ways that meaningfully hurt Russia without any actual violence.
With the respect, the Trump team failed to invade the US Capitol when they controlled it’s defense apparatus, they are more likely to kill themselves than succeed in any ground invasion.