Shepherd doesn't include this as it is quite lean and extensible (service start/stop hooks are functions that can do anything) but Guix includes a Linux container implementation and an abstraction built on top for use by services. The long term vision is to use an object capability security model so, rather than "locking down", a service can only interact with the resources to which it has been passed a reference. No ambient authority, no confused deputies.

I really like systemd but am also Guix-curious. This sandboxing topic has been a bit of a blocker for me to properly go deeper with Guix. Do you know of any good places to read more about this vision? Sounds powerful and unique.

Just to be clear, sandboxing is possible with Guix, with least-authority-wrapper as a built-in option. Regarding the long term vision of capability security, you can read the Spritely (the nonprofit I work for) whitepaper about capabilities and the work we're doing in Guile to make it happen [0]. The paper isn't about Guix, but Guix stands to benefit from the effort. Getting to the point where Guix services are capability secure will take many steps, but one step is bringing capabilities to Shepherd, which we have made progress on through an NLnet grant [1].

[0] https://files.spritely.institute/papers/spritely-core.html

[1] https://nlnet.nl/project/DistributedShepherd/