AppCenter is a fast software store built on top of libappstore (https://launchpad.net/libappstore)

Warehouse is described as 'Versatile toolbox for managing flatpak user data, viewing flatpak app info, and batch managing installed flatpaks' and is a Package Manager in the os & utilities category. There are more than 50 alternatives to Warehouse for a variety of platforms, including Linux, Mac, Windows, Flatpak and Flathub apps. The best Warehouse alternative is UniGetUI, which is both free and Open Source. Other great apps like Warehouse are Chocolatey, Ninite, MacUpdater and Scoop.
AppCenter is a fast software store built on top of libappstore (https://launchpad.net/libappstore)

RPM Fusion provides software that the Fedora Project or Red Hat doesn't want to ship. That software is provided as precompiled RPMs for all current Fedora versions and current Red Hat Enterprise Linux or clones versions.

Spack is a package manager for supercomputers, Linux, and macOS. It makes installing scientific software easy. Spack isn’t tied to a particular language; you can build a software stack in Python or R, link to libraries written in C, C++, or Fortran, and easily swap compilers or...
a program developed by SweetLabs. It comes preinstalled application for customizing your PC from the first time you turn it on.

Solseek is a simple terminal user interface that allows you to browse, search, and manage packages from the Solus packages. Packages can be installed, reinstalled, updated, verified, and removed through the interface.

A modern, delicious implementation of the Nix package manager, focused on correctness, usability, and growth — and committed to doing right by its community.
pkgsrc is a framework for building over 17,000 open source software packages. It is the native package manager on SmartOS, NetBSD, and Minix, and is portable across 23 different operating systems. Use one package manager across all of your systems!
What is Fink?
Fink is a project that wants to bring the full world of Unix Open Source software to Darwin and Mac OS X. As a result, we have two main goals. First, to modify existing Open Source software so that it will compile and run on Mac OS X. (This process is called portin.

The tool allows to easily install multiple programs at once. It creates a setup package that contains multiple application installers. Simply run the package. Programs will be installed automatically in background mode (silently).