Getting dual boot with MX linux

`I bought a StarLab StarLite with MX Linux preinstalled and I want to get dual boot with NixOS. The boot configuration seems a little unfamiliar to me. The relevant entry in fstab is

UUID=4E78-4B66 /boot/efi vfat noatime,dmask=0002,fmask=0113 0 0


$ tree /boot/efi
└── EFI
    ├── BOOT
    │   └── BOOTX64.EFI
    └── MX21
        └── grubx64.efi

My best guess is that if I want the EFI menu to show both systems I should have my configure.nix as follows

boot.loader.systemd-boot.enable = true;
boot.loader.systemd-boot.editor = false; # recommended override
boot.loader.efi.canTouchEfiVariables = true; # came this way
boot.loader.efi.efiSysMountPoint = “/boot/efi”;

Have I got this right ? Thanks in advance.