1-/boot/ on a UEFI installation is impure, containing /boot/efi/, on which is normally mounted the FAT ESP partition.
2-(most or all of) the names of the directories in /boot/efi/EFI/ may be selected by the admin by employing GRUB_DISTRIBUTOR=. When the admin does not do so, each is normally a result of either what each /etc/os-release contains, or what the distro provides for GRUB_DISTRIBUTOR=.
While in openSUSE by default GRUB_DISTRIBUTOR is null, in others it is not, e.g. Debian 10, Linuxmint 19.1, and Ubuntu 18.04 all use exactly this:
GRUB_DISTRIBUTOR=`lsb_release -i -s 2> /dev/null || echo Debian`