I want to bring up this topic also if I can not do the work.
For the rpm based distribution we offer a client repository containing the katello-agent and scap-client, but for Debian and Ubuntu we do not offer this tools. There will be no katello-agent as far as I understood but for registering the systems to Katello we would need subscription-manager (which includes debian packaging instruction in https://github.com/candlepin/subscription-manager) and some package trace upload (can not find it at the moment). OpenSCAP and policies are available, so it would be also only packaging the client gem.
So I think we should provide this for full support of the Debian family and it should be a manageable effort (but I could be wrong).
I would be happy to hear some opinions and estimations of how much work it would be, especially from @mmoll as he does most (or all?) of the Debian packaging, @bernhard_suttner as he knows what ATIX perhaps already did and can provide and @tbrisker for release managers perspective.