Improving .deb

I am not sure I follow what you are wondering about here. The internal low level implementation details of RPM format obviously doesn't affect end users. What matters to end users is functionality like library and file based dependencies or boolean dependencies or weak dependencies etc.

ostree based systems don't use RPM at all and therefore dependencies don't really matter all that much on these systems for end users. What you get is a OS that is constructed and pushed to end users a single "immutable" image and everything else is supposed to be running of containers of some sort. rpm-ostree provides some level of compatibility with traditional RPM packages but the more you use them, the more you move away from the advantages that a immutable base image provides. Instead the recommend path is use wrapper like Fedora toolbox and within that you could just install plain rpm packages.