aurutils VS docker-archlinux-aur

Currently I use aurutils, so that created packages are stored in an extra repository on the respective machine and can be installed through it.

I currently use aurutils.

If I am not mistaken officially maintained packages follow the same initial process as AUR packages. You can read the wiki on Creating packages. But official packages are tested (there is a testing repository with the newest packages) where as the AUR package expects users to do the build and testing themselves, at their own risk in other words. With the helpers like glorious aurutils the process of keeping up-to-date dozens of packages (if you happen to be in a such a use case) with many dependencies is quite easy.

You could use https://github.com/AladW/aurutils to create your own pacman repository on this USB drive. On your powerful PC you build the packages and they are placed in the repository on the USB drive. Then on your other machine you add the repository and install any AUR packages that you added to the repository from there. Dependency resolution would be handled by pacman itself just like for the normal repositories.

aurutils

Check out aurutils, it is a collection of scripts that helps to streamline the process of maintaining a custom-repo for you aur packages. It takes a little to set everything up in the beginning (but it is less work then OPs method). After the initial setup everything just works.

I have yay installed but I've also setup aurutils on my server that automatically builds a list of packages to a pacman repo every day so I can just update them with my other pacman packages. Saves time compiling them during updates and lets me upgrade the same packages on my desktop and laptop without having to needlessly build them twice.