Yes it can. The build daemon already uses containers to create the isolated environments to perform builds in so that we can view builds as pure functions. Nix uses systemd-nspawn for making NixOS containers. Guix uses a Scheme interface that I wrote called call-with-container to build GuixSD containers or simple containers without an init system via 'guix environment'. call-with-container is a work in progress, but some of the code has already made it to master, and the rest of it should land in master in time for the next release.
That's great to hear, thanks for the work, I look forward to trying it out. Using Guix with systemd-nspawn sounds like it could be a formidable combination.
Guix doesn't use systemd, but maybe you could still use systemd-nspawn somehow? call-with-container will be the preferred mechanism on Guix, since it will integrate tightly with the rest of the system.