As an additional note: each label you use must be unique across all of your menu entries.
IE: If you make a menu entry for ESXi 6.5 and another for 6.7, then these lines:
iseq ${platform} efi && goto esxi_efi || goto esxi_bios :esxi_efi ... :esxi_bios ...must have unique labels, for example esxi65_efi vs esxi67_efi instead of both having esxi_efi (or esxi_bios).
If you use the same label in 2 different menu entries than iPXE will go to whichever is listed first in your boot.php.