In OBS, how does one reference another OBS base image for a Docker container build?

One can, for example, base off the latest leap image as follows:

FROM opensuse/leap:latest
But, I can't figure out the syntax for container in a home project.

I tried to use another image in the same subproject:

FROM other_image:latest
But this yields the following from `osc build`:

buildinfo is broken... it says:
unresolvable: have choice for dbus-launch needed by libgio-2_0-0: dbus-1 dbus-1-x11
If I try to use home project syntax as follows:

FROM home:lewellyn:containers:other_image:latest
I get the following output:

buildinfo is broken... it says:
unresolvable: nothing provides container:home:lewellyn:containers/other_image:latest
I do not get that output with any of the opensuse base images, so I suspect my package/project isn't necessarily broken.

For clarity, my eventual goal is to start building my containers in my own OBS instance. But it's generally far easier to get started in the public OBS.

And for that reason, I don't really want to list the package names, as that whole subproject may end up vanishing by the time someone else stumbles down this question in the future.

It seems that it'd be relatively easy to get going, but I'm missing some key information that I don't know. I tried even adding the project to its own configuration as a repository path, but that (obviously) did not work.

Also, I've read in another thread that there are Tumbleweed OCI images, but I can't find those to try to use as base images in OBS either.

Does anyone have any pointers? I have not found any useful information for using Dockerfiles in OBS for home projects beyond Introduction of the new OBS Container Registry - Open Build Service and that page kind of ignores the whole layering approach which is common. I also found Building derived containers - openSUSE Wiki which implies the home:lewellyn:containers/other_image:latest syntax is correct.