> This may be true to some extent, but what I dislike about this idea is that to many it implies that human flourishing is impossible without suffering exported elsewhere

To some degree this is true, in the sense that human flourishing implies some degree of suffering for e.g. the ants we accidentally step on, animals we eat, bacteria in our guts, etc. But Jains do their best not to step on the ants, many people refuse to eat flesh, and so on. Plants and bacteria will have to fend for themselves for now. We can certainly do better with each other.

I am proposing no version of fatalism, besides the fact that, at least in our living substrate, organisms have not all learned to do each other no harm, if this is even possible, and even if it isn't, fatalistic hedonism is not the inevitable response to this fact.