*So first, my TL:DR is basically that communism as an ideology has worked in pretty much every situation it was implemented in, and that evidence backs this up. This far larger piece than I will ever make on this thread is a better read than anything I could ever make *
So, I've already taken the time to do my best defining socialism and communism in a simple and hopefully easy to understand way. Now to answer the meat and potatoes of the question, "a context in which communism could work."
In short, this context is our current context.
First, we'll start off answering your final proposition that communism "maybe communism could work in the U.S., maybe not?" Obviously ignoring the fact that, again, communism has repeatedly succeeded in raising the standard of living of the working class, it is generally accepted that countries like the USA and UK will be the LAST to adopt a communist ideology.
The reasoning behind this is that, as the largest imperialist nations of the world, there is a vested interest in suppressing any ideology that poses a real threat to capitalism. As the UK and USA are dictatorships of the bourgeoisie, their interests lie with the bourgeois interests. Because of this, and their history of being the two most imperialist nations in the world, they have spent decades manufacturing consent through propaganda, playing into the idea that the proletariat may one day become a part of the bourgeoisie in order stifle any revolutionary potential. Or, in a fun quote!
"Socialism never took root in America because the poor see themselves not as an exploited proletariat but as temporarily embarrassed millionaires." – John Steinbeck
This is in contrast to what Marx and Engels predicted, that capitalism would be overthrown first in the developed nations. The reasoning behind this, from my understanding, is due to the substantial increase in imperialism. It is now generally accepted that it is the weak links of capitalism, the most exploited nations (Russia, China) that would see communist revolution first.
As for the meat of the meat and potatoes, the proposition that "a context in which communism could work" (referring to the ideology) inherently implies that communism hasn't worked. This is false, blatantly. Time for statistics sorted by nation.
The USSR:
The first ever socialist nation, the USSR was a nation that came from nothing. Its workers were serfs and faced with regular famine. This nation received the harshest doses of propaganda (until its collapse, when rhetoric eventually focused to China).
However, contrary to what this propaganda would tell you, socialism did not fail in the USSR. It succeeded, repeatedly and often. It elevated the lives of people to extents they never saw before or (for the most part) since.
First, the USSR saw some of the highest growth of quality of life in the world (including under Stalin): https://www.cambridge.org/core/journals/slavic-review/article/abs/great-leap-upwards-anthropometric-data-and-indicators-of-crises-and-secular-change-in-soviet-welfare-levels-18801960/B7C984FD62885FF22095D8C641BD7237
Second, even economically the USSR had a supremely fast growing economy: https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.507.8966&rep=rep1&type=pdf
Third, contrary to popular propaganda, the USSR was not a nation of famine. In fact, one of the greatest achievements of the USSR was ending the cyclic and rapid famines that plagued Tsarist Russia. Soviet citizens had a higher average calorie intake than US citizens (https://www.cia.gov/library/readingroom/docs/CIA-RDP84B00274R000300150009-5.pdf). The famines that affected the early USSR were not malicious, but caused by factors including bad weather, poor economic planning, and the deliberate destruction of livestock and grain by kulaks to avoid collectivisation.
https://www.palgrave.com/gp/book/9780333311073#aboutBook
The USSR was dissolved illegally, against the will of its citizens (https://en.wikipedia.org/wiki/1991_Soviet_Union_referendum) that seeked to rape Russia of its resources. After the collapse of the USSR, all of its nations experienced a massive drop in quality of life that many still haven't recovered from today. Unemployment, corruption, inequality skyrocketed. This is one of the many reasons why many citizens of the former Soviet Republics (the majority, in many nations) express that the collapse of the USSR was a bad thing. And though they do not find the Soviet Union without fault, they agree that it was preferable to what followed. A common joke in many former socialist states today is:
"What did capitalism do in 10 years that communism couldn't do in 70 years? Make communism look good."
Now, I think I'm running out of space, so I'll really cover China and Cuba next! Nations like the DPRK, Laos, etc are best covered by the first link I provided.
China. The modern boogeyman of the west. China is the largest threat to western hegemony thanks to its massive industrial base and population. As such, it is the target of the most propaganda.
We'll mostly talk about Mao, because although I'd love to talk about modern China lifting millions out of poverty at a rapid rate, most of the best links relate to Mao. It's also nearly 11, and I've got the attention span of a magpie. So expect these next arguments to be more of a link dump.
Long story short, China in the 50s was a nation with 7% of Haiti's current GDP. Despite having a colossal population, loads of land, it was poorer than the poorest country in the Caribbean. Of course, we can see how communism (even revisionist communism) treated China today compared to Haiti.
Mao's achievements are immortal, even considering his massive failures. He is considered 70% good 30% bad for a reason. He lead the People to victory against both the Japanese and the far-right Kuomintang. He nearly doubled the lifespan of China in 50 years (this statistic DOES take into account deaths from the Great Chinese Famine, the last famine in Chinese history) and put it on the path to become the next superpower.
As for Cuba, every communist loves Cuba. It's considered by most the most successful socialist nation in the world. It has plenty of achievements of its own, so I'm just gonna list them.
DESPITE A DECADES LONG BLOCKADE, CUBA…
Is the first nation to eliminate mother-to-child HIV: https://www.who.int/mediacentre/news/releases/2015/mtct-hiv-cuba/en/
Has largely eliminated hunger and poverty: https://www.wfpusa.org/countries/cuba/#
Has a better literacy rate, life expectancy and paternal care than the USA: https://www.unicef.org/cuba/
Is the only country in the world to live up to the sustainability standards put forward by the WWF: Cabello, Juan José; et al. (2012). "An approach to sustainable development: the case of Cuba". Environment, Development and Sustainability. 14 (4): 573–591. doi:10.1007/s10668-012-9338-8. S2CID 153707220.
Remember, this is from a tiny nation bordered by one of the most anti-communist nations to ever exist, with virtually no worthwhile natural resources. Despite this, Cuba is a world leader in the Caribbean.
In short, this world is the world in which communism works. Time and time again it has shown itself to be the most effective method of eliminating poverty, solving the contradictions of capitalism and establishing high quality of life, even despite constant hostility form the wealthiest nations in the world.