The numbers below are for a project with one cube, one camera, and one scene. None of the standard or other assets were included.
The upshot is that around 14MB of “something” extra (i.e., debug symbols) is being compiled in. Since there are only three objects in the entire project, this seems a little excessive. I bring this up because I have noticed that builds can get ununusually large. I wasn’t sure if this was an artifact of running Unity on an Intel Mac, or if this was normal behavior. I do understand that around 10MB (spread between the frameworks and the binary) is the minimum to provide core functionality.
Universal Binary
Zelda:~/Desktop/test_unity_project/build_with_cube.app/Contents flip$ du -sk * | sort -n
4 Info.plist
4 PkgInfo
24 Data
1348 Resources
8668 Frameworks
29036 MacOS
Zelda:~/Desktop/test_unity_project/build_with_cube.app/Contents flip$ ls -l MacOS/
total 58072
-rwxr-xr-x 1 flip flip 29731960 Apr 8 11:09 test_unity_project
Intel Only
Zelda:~/Desktop/test_unity_project/build_with_cube_intel_only.app/Contents flip$ du -sk * | sort -n
4 Info.plist
4 PkgInfo
24 Data
1348 Resources
5252 Frameworks
19948 MacOS
Zelda:~/Desktop/test_unity_project/build_with_cube_intel_only.app/Contents flip$ ls -l MacOS/
total 39896
-rwxr-xr-x 1 flip flip 20425120 Apr 8 11:17 test_unity_project
Intel Only, strip debug
Zelda:~/Desktop/test_unity_project/build_with_cube_intel_only_stripped.app/Contents flip$ du -sk * | sort -n
4 Info.plist
4 PkgInfo
24 Data
1348 Resources
5252 Frameworks
5712 MacOS
Zelda:~/Desktop/test_unity_project/build_with_cube_intel_only_stripped.app/Contents flip$ ls -l MacOS/
total 11424
-rwxr-xr-x 1 flip flip 5846888 Apr 8 11:21 test_unity_project
Intel Only, compress textures and strip debug
Zelda:~/Desktop/test_unity_project/build_with_cube_intel_only_compress_and_strip.app/Contents flip$ du -sk * | sort -n
4 Info.plist
4 PkgInfo
24 Data
1348 Resources
5252 Frameworks
5712 MacOS
Zelda:~/Desktop/test_unity_project/build_with_cube_intel_only_compress_and_strip.app/Contents flip$ ls -l MacOS/
total 11424
-rwxr-xr-x 1 flip flip 5846888 Apr 8 11:20 test_unity_project