US energy use is ~2x higher per person though than Europe or China, giving much more room for reductions.
So you'd expect emission changes in China to require the most "effort" (difficult to cut emissions while energy demand/use grows), followed by Europe (where energy use is already down to current chinese levels and demand/use is decreasing), while making progress in the US is by far the easiest since you very high baseline makes it much easier to cut/reduce.
This tracks with political reality I feel.
Energy use: https://ourworldindata.org/grapher/energy-mix?tab=line&count...
CO2/capita (basically the same): https://ourworldindata.org/grapher/consumption-co2-per-capit...