No update from our side, sorry, In the meantime GitLab supports URLs with a subdirectory. Hence this request is not directly relevant any more for us. Our current issues are more about how to proxy from https://gitlab.our-org.com/gitlab to https://gitlab.internal/ as lined out in this [Reverse Proxying relative URL to root URL results in 404 errorpage (#37028) · Issues · GitLab.org / GitLab FOSS · GitLab] issue and this [Reverse-proxying relative URL to root URL results in 404 errorpage] thread.