Some things I had to do to get my react native app running on iOS simulator:

If there is a boost error during ‘pod install’ go to node_modules/react-native/third-party-podspecs/boost.podspec

There change spec.source to

{ :http => 'https://archives.boost.io/release/1.76.0/source/boost_1_76_0.tar.bz2', :sha256 => 'f0397ba6e982c4450f27bf32a2a83292aba035b827a5623a14636ea583318c41'}

If you get flipper errors trying to build, go to ios/Podfile

Change flipper_config to

FlipperConfiguration.disabled

and comment out this line:

:flipper_configuration => flipper_config

Apparently it’s not needed anymore.