I haven't seen either film. I didn't see Barbie because I'm waiting for all the hype to die down (and it's yet another example of white centered femininity, for me) and I didn't see Oppenheimer (because I didn't have to budget to go see it,) but I also didn't feel like watching yet another movie sympathizing with another of America's "Great White Men" that white filmmakers love to worship onscreen!
Sometimes, I think both films sum up Americas general pop culture history of white male directors thinking they're saying something important, and white women filmmakers thinking they're saying something deep, but both of them are just saying the same message we've all heard about a million times in the past hundred years.