Packaging for Nix and Flatpak is sufficient. Distros can do distro-specific packaging, but both Nix and Flatpak are installable on most distros if a user’s distro doesn’t package it.

Also, once you have a functioning build using Nix, you can easily generate .deb packages with it. Nix is also fairly low maintenance, although it can be a lot of upfront work depending on the project.