The in-game docs aren't built otherwise, so you won't get help for the various commands if this isn't set.
As $HOME shows /root under sudo
This depends on a new entrypoint put inside the docker image, that will read BUILDER_UID and fix up the users and files. This also removes "sudo" and allows the entire script to be run with sudo without messing with the build file permissions.
That will simply generate the win64 artifacts for those of us that run DF under Proton on Steam for Linux.