This might be an xy problem.
What are you trying to solve?
If you’re just trying to have access to an community package manager.
One of these might be more useful.
https://nix.dev/manual/nix/2.34/quick-start
If you specifically must have the AUR. I suppose you could install arch in a container like you suggested.
What do you mean by “entire” distro? The distro itself doesn’t download the “entire distro”, it’s made up of packages, like almost every distro is. You’re only installing the base system, the packages are where the rest of the downloads come from. What “parts” of the distro’s base system don’t you want? The dockers are already pretty stripped down and minimalist by default, I’m not sure what else you could cut out to still have a functioning OS?
Sure, just install paru or yay and proceed as normal.
Just by installing paru, aur can be downloaded ?
You don’t download or install aur itself. It’s a repository of packages.
Helper programs like paru make it easier for you to connect to, search, download, build and update packages from the repo.
You can also use other methods, for example ‘git’ to clone the source for the package and build it yourself, but the helper programs should also help fetch dependencies.
As with everything in arch, the wiki is recommended reading: https://wiki.archlinux.org/title/AUR_helpers https://wiki.archlinux.org/title/Arch_User_Repository
