Emissions per capita is not a good metric. It favors states which have millions of people who are living in poverty and who thus by definition have low consumption, which translates to low emissions. The downside of course is that these people are starving.

If you imported 200 million people into the US in poverty conditions and did nothing to improve their situation, then all of a sudden US per capita emissions would look great too.

In the worst case scenario if you attach policy to this metric you might see states gaming it by deciding to make sure their poor people stay that way (probably already on the minds of policy makers in some authoritarian states).

Admittedly I don't have numbers handy, but I think it would be better to look at emissions generated per dollar of economic output, particularly in industries that generate the most emissions. Then you can start inferring judgements about whether it's better for humanity to open a new factory in China or in the USA, and those two states have to compete on cleanliness if they want to grow their economic output. I bet this sort of measurement would paint the US in a much more favorable light than per capita (and the EU even better). If adding the next $100B to the world economy in the US or EU is cleaner than adding it in China, why shouldn't we push for that?