Something I’ve never seen talked about is the foreshadowing of Al’s words at Trisha’s grave early on in the series.
When the Elric brothers are sitting at the grave, Al says “I’m cold. I’m hungry. Let’s go home” Right after this, Ed brings up that they should attempt to bring their mom back. At first what Al says seems like a normal thing a little boy would say but when you think about how each thing he mentions is affected later on his statement holds much more weight.
As it turns out, because of the transmutation, Al can’t feel anything (rain, cold, etc) and can’t eat (doesn’t get hungry), and because the brothers burn down their house, they both can’t return home.