Grub gets installed to whatever you have mounted in /boot/efi as you noted. If you want to specify a particular partition to be mounted there then you should do so during installation. For it to work however, that partition must actually be an EFI type partition, not just an arbitrary data partition.
Grub gets installed to whatever you have mounted in /boot/efi as you noted. If you want to specify a particular partition to be mounted there then you should do so during installation. For it to work however, that partition must actually be an EFI type partition, not just an arbitrary data partition.