If something is packaged for a disto, then I can download it using the package manager and it should theoretically be compatible with the distro and the other packages available through the package manager. But if something isn’t available via the package manager, I could still find it online and download and install it, but it might cause issues because it hasn’t been verified by the people who maintain the distro’s package manager accessible repositories. Or I could still install it with flatpaks or snaps and something something container and it should still work? Or might cause compatibility issues?
And you’re saying that AUR has more packages that have been verified for arch than OpenSUSE has with Yast?