May I know why instead of an RFE for a migration to have those
features, haven't you already set up one much like what a GNU/Linux
distro usually sets up to collect things pending upstream intake?
I'm sorry but I don't understand this question. We are talking about adding a gitlab workflow to the existing mailing list workflow so that gitlab/github users are happier and more prone to contributing. I don't understand what you are asking about this topic.
Additionally, if some packages are better maintained external to the
core Emacs, why not let them be so rather than trying to bringing them
contributing directly to the core?
Again I don't understand what external packages have to do with the topic. We are not talking about including external packages to core Emacs.