Hello and sorry for the delay of my reply.

For your first question see my answer here: https://www.pmbaty.com/iosbuildenv/help/thread.php?path=Problem%20solving/&file=missing-header-files&page=1#i1ltxz9l23g

About your second question, that's unfortunately the way CocoaPods works. And since Unity recreates your project directory each time you export a Xcode project, the Pods folder is deleted and CocoaPods has to do it all over again. I believe the same is true on macOS.

My advice is to allocate time to gather the precompiled frameworks your project needs, then build the necessary compiler and linker flags to use them, and inject them in your build. And no longer use CocoaPods. This will save you a lot of time in the long run, at the expense of some initial search.