Visit any project in gerrit and click its Access tab, e.g. https://gerrit.wikimedia.org/r/#/admin/projects/mediawiki/skins/Vector,access
Note the
History: (gitblit)
line links to git.wikimedia.org.
I assume it should eventually link to Diffusion. I don't know if it's possible to access project metadata like /refs%2Fmeta%2Fconfig/project.config from Diffusion.