As @wh33zle mentioned, CI/CD is an obvious use-case. Development environments is another one (pls see the other question i just answered on this topic).

But i also see 'production' scenarios. Think about having a reverse-proxy system container, inside of which you host the backend applications, which happen to be docker containers.

In essence, Sysbox allows you to create hierarchies of containers in a secured fashion, without the need to abuse 'sidecar' pattern, nor priv containers.

I use dind to build containers in gitlab ci.

Try using Kaniko with GitLab CI, it will save you from having to run privileged / DIND containers.

I've been experimenting with buildah, but that does look like another option I should try, thanks.

For example, my CI provider might want to execute my build in a docker container for security reasons but I also want to run/build a docker container as part of my CI.

I think you'll also need it if you want to use docker-compose in your CI.