Alternative rosdep in catkin/catkin-tools plugins

I have al alternate use-case for custom rosdep sources. In my group’s current workflow, we are generating debian files for some of our “custom” dependencies and hosting them privately on-premises. In order to use them in our CI/CD pipelines, we need to add both apt and rosdep sources.

I’ve seen examples of adding apt sources for snapcraft builds (although I haven’t tried it yet), but there doesn’t seem to be support for adding rosdep sources anywhere. I was going to add them manually using custom steps in my snapcraft.yaml, but a quick glance at the source code suggest anything I do will be wiped out right before updating rosdep.

Am I missing something here?

Otherwise, considering one of the selling points of snap as a packaging tool w/ respect to the ROS buildfarm is that it better supports private developments, I think this feature should be reconsidered.