No, each distro manages its own entry separatly from the other distros…
When it comes to sdboot-manage, IMHO that is buggy as hell and i prefer to write my own hooks…
And it’s no hassle at all from a distro pov. compared to what else they need to customize, a small text file can hardly be labeled as such…
Wrong thats not the job of the bootloader, its the job of the bootloader configurator.
About grub doing that automatically, you’re wrong update-grub aka “the bootloader configurator” is creating the menu entries.
Grub does not generate menu entries at runtime…(But sd-boot actually can and does for firmware setup, efi shell and M$)
I solve that by mounting the ESP at /efi and do a bind-mount of a subdir of the ESP as /boot eg:
systemd-mount -o bind /efi/Manjaro /boot or inside fstab or like me in (auto)mount units…
So in short grub looks like it is easier because it already has scripts doing all the needed heavy lifting, while sd-boot (Systemd-boot) does not yet, which will change as time goes by and more and more people use it
BUT…we’re walking off-topic…