I’m and end user
Yeah, we all are. What's your point?
End users are also developers. All computer users are developers. You are developing.
user working for end users
By making a script that lets me get backdoors and shitty packages with ease? The linux package distribution system is a nightmare, Debian is the least bad approach. There is basically always a better option to using a .deb file. If you come across something that isn't packaged, I recommend Flatpak, building from source (and installing unprivileged), or using the developers vendored tarball (installing unprivileged).
https://wiki.debian.org/SecureApt
By using local .debs you lose the benefit of:
Reproducible builds
GPG checksums
Stable release model
debian security team