update-notifier VS aptly

You should ask in the upstream bug tracker (is it this one? https://github.com/lubomir-brindza/nautilus-typeahead). First step is to get it to build for Debian manually/locally - i.e. patch the official nautilus Debian package. Then it's easy to setup a personal APT repository with aptly

Exactly what aptly is for. No idea about CentOS side, for that we just had rsync from official repo + some scripts

I'm not sure if this is an option, because it might break the isolation model, but you could setup repo mirrors in whatever tool of choice you like, but for Debian/Ubuntu, I think aptly is really featureful.

I know that it is not directly what you asked about, but without knowing how the signed debs are being used, I can say that if you were to use aptly to create an apt repo to house your debs to then be installed on whatever machines offline (assuming network connectivity, which may be an incorrect assumption), it requires you to sign a published repo/mirror, and also requires you to install and trust the key on any systems that you then want to use to install package unless you specifically use [trusted=yes] in the apt repo list file.

There's also Aptly but I've never used it. Looks neat, though.

I personally just mirror the packages for what ever I'm using with aptly and use the netinstall iso and point it to that local mirror. The netinstall iso will pull any needed updated from the repo.

Take a look at Aptly.

Aptly is a purpose-built DEB content management solution. Never used but I've heard good things.

The last time I got involved in repo/package management, we used aptly Later moved to Jfrog artifactory. The latter is very expensive.There is also pulp some said it is good, which I personally never managed in production environment, so I can't recommend for or against.