I actually liked how some scenes (mostly in the first and last thirds of the movie) jump back and forth, while maintaining a good narrative flow, but damn if I can remember who is who.
It’s not as confusing as Memento, nor Primer, and it doesn’t need to be. I think the use of nonlinear storytelling here is to highlight how each character has faced the consequences of their achievements (as a group, or indivually). The line Albert Einstein gave Oppenheimer at the end of the film drives this point home.
IDK though, I think I missed a good chunk of the movie by spending most of it trying to remember who’s who.