Per capita figures are meaningless. You're discussing imaginary lines in the dirt. The only way to tackle climate change is to bring down global emissions.
The best fair first approximation to this is for each country's share to be proportional to its population. That can then be refined with some sort of emissions trading system so that countries that want to outsource high emission industries to others can provide the emissions budget to allow that work.
Anything other than a per capita first approximation requires deciding that some countries simply are not going to be allowed to develop beyond third world status.
At projected 2050 population levels of 10b, and 25GT/year emissions, per capita emissions allowance is 2.5t/year. There is no industrialized country with this level of emissions, the lowest being Sweden, Switzerland and France at 4.5, 4.7 and 5.13. These countries have moved >90% of their electrical production to nuclear and renewables and cut their emissions in half compared to the 1990s. Possibly they are also externalizing their food and industrials production.
B. What is 'fair' share? Population as of 2020? 2050? 1950? Land area? Forest mass?
The most obvious issue is population. Hard to believe, but in 1950, at the beginning of the current Golden Era, world population was a mere 2.5 billion people. At those population levels everybody on Earth could have had afforded the industrialized lifestyle of Japan, Germany or Netherlands, with about 10 CO2t/capita emissions.
The US, Canada and Australia together make up roughly 20% of global emissions with approximately 5% of the global population. Regardless of how you slice it these countries need to take serious action.
Let's just focus on plugging the latter shall we, while we all go down together.
You’ll notice that per-capita emissions are highly correlated with the list of countries that export fossil fuels.
I agree with your point but per capita emissions alone is a gross oversimplification.