“The Chinese or Russians...We’d have nothing they want.”
The Chinese or Russians would be very busy dealing with their own weather/crop calamities. A Y eruption similar to the one 600K years ago would probably lead to several BILLION deaths by disease, starvation and war.
Imho, the main problems in the US would be infrastructure failure, particularly for older people who live alone, and cities in the path (or experiencing electrical supply failures as a consequence of the eruption for example). If a big enough eruption happened in just the wrong place, your figure is at least high enough, maybe too low. Just about a century ago there was a monsoon failure in India leading to drought, crop failure, and starvation, and there simply was no way to cope with it. With India’s current population, if an eruption gave a similar result (crop failure, drought, cold, etc), it would have an impact on more than a billion Indians, and perhaps hundreds of millions of others in southern and SE Asia.