Devenv once introduced an"feature" that uploaded your entire repo to a secret server to train their AI and didn't understand the backlash they got. There's no way they should ever be given a second chance. It is not a good recommendation.
MZLA Technologies, the Mozilla subsidiary behind Thunderbird, has launched Thunderbolt, an open source, self-hostable AI client aimed at organizations that can't send sensitive data to third-party AI services.
I do not understand your issue. If skills are simple files, why not copy them into your nixos configuration directory? Or run whatever tool exists to download them into your nixos configuration directory and commit it to git.