Aguamarina is a package manager for legacy versions of android forked from Aptoide, supporting most legacy Android versions, including Android 1.0, though it will likely not work as intended on newer Android versions.
Legacy iOS versions have a thriving community of sideloaders, with Cydia acting as the definitive package manager.
Legacy Android versions do not have a thriving community at all, with existing package managers like Aptoide, APKtor and F-Droid being difficult to create repositories for on modern computers and not being very accessible. Aguamarina aims to fix these issues and possibly help start a bigger community of legacy Android users.
Using the Berilo Rojo php scripts, you can generate a repository. Repositories consist of 2 XML files (info.xml and extras.xml), apks and icons. A user can add your repo to their Aguamarina client easily.