pxe_kernel_options are not handled in Preseed PXE templates. These are very useful for Debian-based systems, e.g. to set:

ethdetect/prompt_missing_firmware=false

which can only be set before the network is activated to load the preseed file (cf. https://community.theforeman.org/t/adding-pxe-boot-kernel-commandline-options-for-preseed-based-systems/25561 ).

A PR to add this support is coming up.