Update: gave a shot to switching to systemd-boot today.
sudo cp -a /boot/. /boot.baksudo umount -R /boot-
sudo rm -r /boot/*(though preserving my raspberry pi UEFI stuff) - Minor config changes such as
boot.loader.systemd-boot.enable, deleting the mountpoint for my ZFSbpool, changing/boot/efito/boot sudo nixos-rebuild --install-bootloader switch- reboot
One new warning, otherwise so easy it was quite boring. Thanks for the kick in the pants, I didn’t realize it was the blessed approach in the nixos manual.