Good catch guys. 
Also, @ozotto you can check
ls /boot/efi/loader/entries/
If GRUB2-BLS is in use there will be .conf files present for openSUSE.
If this is the case it should be possible to add an entry for Ubuntu as well. Create a file like
“/boot/efi/loader/entries/ubuntu-studio.conf” with
title Ubuntu Studio 24.04
efi /EFI/ubuntu/grubx64.efi
then reboot and it should be present in the menu.