IIRC it was a bit more convoluted than that. Unity was using Mono AOT for iOS at the time when Apple announced that iOS was moving to ARM64, I think Mono alread

IIRC it was a bit more convoluted than that. Unity was using Mono AOT for iOS at the time when Apple announced that iOS was moving to ARM64, I think Mono already supported ARM64 AOT but Unity was stuck on an old version which was 32bit only because they were unwilling to pay whatever Xamarin was charging for the new version (Mono had a dual license like QT back then). IL2CPP was originally developed for the WebGL build target (pre web assembly it went .NET -> cpp -> javascript). After the Apple announcement it was hastily ported to work on iOS. Initially (and maybe up to a couple of years afterwards to some degree ) it was extra buggy and the build time was extremely slow, but I think it was probably worth it in the end.