As of now, bootloaders are hardcoded to syslinux,grub-efi. If someone wants to change that, they can only edit data/defaults.toml, there's no way to specify that per flavor or at build time.

Proposed syntax:

For flavors:

bootloaders = 'syslinux,grub-efi'

For one-off builds:

sudo ./build-vyos-image --bootloaders 'syslinux,grub-efi' generic