Trying to install NixOS from chroot, getting "System has not been booted with systemd as init system"

I’ve installed NixOS onto a flash drive that I’d like to turn into a bootable usb, however when I try to boot into it there aren’t any generations to choose from, the only option on the bootloader is to return to my uefi firmware settings

Currently I’m trying to use nixos-rebuild switch under chroot (specifically the nixos-enter command) to create a new generation to boot into, but I’m running into this error whenever I try to build my config:
“System has not been booted with systemd as init system (PID 1). Can’t operate.
Failed to connect to bus: Host is down”

The output from ps aux shows that systemd is my init system:
root 1 0.0 0.0 22552 14244 ? Ss Apr24 0:02 /run/current-system/systemd/lib/systemd/systemd

Any ideas for this? Thanks

It means the system you’re chrooting into, nixos-rebuild switch will try to enable/disable/restart services when switching.

IIUC nixos-rebuild boot should work just fine, as it only sets the new system as the next boot default.