I’ve never found that either. I try to limit my interactions with GitHub to copying the URL to clone and doing pull requests. GitHub has the same relationship to Git as OverLeaf has to LaTeX: a layer of excrement smeared over and defacing a beautiful program. The saddest thing is that much of the current generation of programmers think that GitHub is Git.
`git log --graph --decorate --oneline` is specific to a branch of a repository. Github Network shows the relationship between forks. It is similar but really the question answered by it is "what and where is the work being done" and "what is the relationship between work being done and this repository I'm looking at". It sucks that Network is buried, I think it should be much more accessible.
Eg https://github.com/sindresorhus/delay/network tells me that this work is being maintained actively, but most forks are not merging back. Another one might tell me work on the main fork is stalled, and many users are now doing PRs against a fork of the original.
Maybe git log --graph --decorate --oneline --all then? Github implements forks as just fancy branches in the same repo. Adding the all param includes all branches.