Pacman plus the AUR is the move on Arch based distros. The AUR gives you access to basically everything, and paru or yay handles the build chain without pain. Flatpak has its place for apps that ship messy runtime dependencies, but for most things it adds an unnecessary isolation layer. Have you tried paru as your AUR helper yet?

The AUR really does make Arch-based distros feel complete compared to other options. That massive package ecosystem covers most needs without hunting around random websites, though occasional build failures still happen. Have you tried any of the AUR helpers to manage updates and orphan packages?