Maybe this can be explained similarly to someone through whom a sin requiring a guilt-offering came about unknowingly, and even under compulsion, who is liable for an offering, because in the end reality was damaged through him. In the same way, someone through whom reality was improved, even under compulsion and without intention, deserves a blessing.

I think the idea of blessing here is something along the lines of “the reward of a commandment is a commandment,” and in parallel, “merit is brought about through one who is worthy.” Meaning, you did well—you did something good, and that itself is a blessing.

Oren, maybe. That’s a kind of spiritual mechanism about which I have no real grasp. You just have to remember that under compulsion there is no offering, meaning that the act in itself is not considered a sin, and therefore on your approach it also should not bring spiritual benefit.

There are offerings that are brought even for acts done under compulsion, for example the nazirite guilt-offering.

With guilt-offerings in general, that is their very nature. See my article:

מהותו של קרבן אשם

Maybe not every commandment involves this, but it’s possible that charity specifically does, because it’s well known that with charity the emphasis is more on the result and less on the intention.

The difference between action-commandments and result-commandments doesn’t seem relevant to me for the question of whether reward is deserved. There is a unique rationale for charity, and I wrote it above.