How do I change the icons and labels in the MacOS boot manager?
Rename “EFI Boot” in Startup Manager:
Open up a Terminal and use the following commands:
diskutil list - use this to find the Windows EFI partition
sudo diskutil mount disk0s1 - whereas &quot;disk0s1&quot; is your EFI partition
sudo bless --folder /Volumes/EFI/EFI/Boot --label Windows - whereas &quot;Windows&quot; is your label of choice
Rename “Macintosh HD” in Startup Manager
Similar to above, but:
sudo bless --folder /System/Volumes/Data --label MacOS - whereas &quot;MacOS&quot; is your label of choice
Missing/Wrong Boot Manager Icon
Reboot in recovery mode (command+R at boot) and use a terminal to run
csrutil disable
… which disables SIP protection
For Mac side:
sudo cp /System/Library/Extensions/IOStorageFamily.kext/Contents/Resources/Internal.icns /System/Volumes/Preboot/.VolumeIcon.icns
This will change the Mac/Macintosh HD boot icon to the default internal drive icon, but you can just copy whatever .icns file you wish to that location.  See other posts for info on making your own .icns files.
For Windows side:
sudo diskutil mount disk0s1 - Whereas disk01 is the name of your Windows EFI partition from above
sudo cp /System/Library/Extensions/IOStorageFamily.kext/Contents/Resources/Internal.icns /Volumes/EFI/.VolumeIcon.icns
Don't forget to enable SIP protection again, if you wish, by booting back into recovery mode and using:
csrutil enable