It’s true.
For reference here are some of the tools that are available for GitLab.
Julia TagBot for GitLab
Written in python and hosted on github 
Registrator Web Interface / JuliaHub
I am not sure if JuliaHub uses the Registrator web interface with new CSS, or if it has its own system.
But there is a web interface for Registrator that can be self-hosted and works with GitHub and GitLab.
And JuliaHub supports both.
Off of github/gitlab I think you can use RegistryTools.jl to generate the changes to a registry for an arbitary repo so you can PR the registry directly (though you will need to ask for manual merge).
I wouldn’t be suprised if @GunnarFarneback had some nicer front end
Probably GitHub - triscale-innov/RegistryCLI.jl: Manage private Julia registries from the command-line can do it if you point it at a clone of the General Registry (rather than a private one)