Male life expectancy in the US and UK at least seems to have stalled or declined on average over the last ten years.

See Gap minder: https://www.gapminder.org/tools/#$ui$chart$cursorMode=plus;;...

I wonder how it looks for the subset of the US that generally isn't fat, affected by opiods, or unable to get basic healthcare. Obviously it'll be higher, but is it still growing or has it also stalled?

There is a cause and effect problem here, it's possible that modern economies are producing environmental contaminants which cause obesity and other problems ( hormone disruptors are complex ).

The trend of obesity and declining birth rates is common across all developed economies. As a possibility, the accumulation of non-degradable hormone disruptors may have a cumulative effect causing the problem to grow as the decades go on.

It is possible, but I think, unlikely to be nearly as important as change in diets. The poor are much fatter than the wealthy. Do we really think its because they're exposed to more hormone disruptors? Or is it a terrible diet because they don't have the time and resources and knowledge and stress to eat healthier? Contaminants are probably a problem, and could accumulate non linearly into an even bigger problem. But obesity is almost certainly a diet problem. The poor are much more likely to eat high calorie, low nutrient food. Homeless people are increasingly both hungry and fat. I don't think its especially controversial to say that's the likely outcome if you were to just remove these chemicals back to 1800s levels.

While poor diet is certainly the leading hypothesis, the universality of the effect across both Human and Animal populations is worth further consideration.

The poor are vastly more likely to live in areas of higher industrial runoff, to use older materials/homes/appliances, have poorer water quality, and have fewer resources to counteract negative effects in the environment.

Whos quality of life is increasing?

Of people living in the Western world at least, and in most cases 3rd world countries too.

You'd have to be very silly to say that the life of someone in the lowest rung of the working ladder nowadays(e.g. a McDonalds worker) is not better than the life of a peasant in feudalistic times.

Peasant feudalistic times are so far in the history that they are irrelevant.

When people talk about quality of life going up and down, they mean compared to last 20 years or something like that.

Comparing with a previous generation or two, how does a 25 year old's life compare now compared with 2001, 1981, 1961 and 1941

I don’t think you can make that generalization

When discussing short term changes, it's logical to compare to short term pasts.

I get your point, but at least in this case we should probably compare to quality of life just before these chemicals were in use.

I think in the US, life expectancy has been trending down, at least for males.