Listers won't work to fetch metadata for all forges. [[ https://developer.github.com/v3/repos/#list-all-public-repositories | On Github ]] and [[ https://developer.atlassian.com/bitbucket/api/2/reference/resource/repositories | on Bitbucket ]] they don't get any metadata other than the description (and on Github, whether it's a fork). [[ https://docs.gitlab.com/ee/api/projects.html#list-all-projects | On GitLab ]] they also get the number of stars and forks, but not much more.
Existing package loaders currently load some metadata, but we may want to use dedicated loaders for that, eg. with a speicifc visit type.
Or have a new kind of component outside listers and loaders (eg. if we want to use [[ https://developer.github.com/v3/repos/#list-organization-repositories | Github's endpoint to list an org's repos ]] like [[ https://github.com/etalab/data-codes-sources-fr/blob/master/github.py | etalab does ]])