Pyinstaller on Windows versus Mac and why doesn't the correct icon appear on the Windows version?

Question

I'm using a Mac with OS 11.6.1 and running Windows 10 on the Mac with VMware Fusion. I've used Pyinstaller in both environments to create a simple .app and .exe, respectively. I have one specific question and one general question that I'm seeking assistance on:

Question 1:

1. In my .spec file for the Mac version, I included icon='/Users/MyName/Desktop/myicon.ico' as a parameter in app=BUNDLE. Everything worked fine and the icon appeared as desired.

2. When I tried the same thing in the Windows version, using // instead of /, my icon did not appear as I wanted. This was true regardless of whether I included the .ico in datas.

For the sake of thoroughness, here's the complete .spec file:

block_cipher = None
a = Analysis(['my_program.py'],
         pathex=[],
         binaries=[],
         datas=[('C:\\Users\\my_icon.ico','.')],
         hiddenimports=[],
         hookspath=[],
         hooksconfig={},
         runtime_hooks=[],
         excludes=[],
         win_no_prefer_redirects=False,
         win_private_assemblies=False,
         cipher=block_cipher,
         noarchive=False)
pyz = PYZ(a.pure, a.zipped_data,
         cipher=block_cipher)

exe = EXE(pyz,
      a.scripts, 
      [],
      exclude_binaries=True,
      name='my_program',
      debug=False,
      bootloader_ignore_signals=False,
      strip=False,
      upx=True,
      console=False,
      disable_windowed_traceback=False,
      target_arch=None,
      codesign_identity=None,
      entitlements_file=None )
coll = COLLECT(exe,
           a.binaries,
           a.zipfiles,
           a.datas, 
           strip=False,
           upx=True,
           upx_exclude=[],
       icon='C:\\Users\\my_icon.ico',
           name='my_program')

I'm wondering why this doesn't produce the desired icon. Could this be the nature of my icon itself? I simply went online and found a site that converted a .png to .ico and .icns.

Question 2:

When using Pyinstaller on my Mac versus on Windows, I've observed a different folder structure for the results. Both programs are contained in dist, but things are organized differently.

If I'm creating "my_program" the structure is as follows, where "<" means "is contained in."

Mac: my_program.app < dist as well as my_program folder < dist but the app and the my_folder are separate. (The folder contains many things, such as numpy.)

Windows: my_program.exe < my_program folder < dist

Is this the correct way things are organized? I've noticed that I can't open my_program.exe after it's moved to the desktop, which makes me wonder if I'm missing something.