GH have forks. Those are distributed repos. You can also sync to GitLab and similar, you can front it with the likes of Gerrit, integrate some code review UIs that actually clone code, etc.
You can exercise distributed nature of git with GitHub quite well.
There is huge array of alternatives between git-flow and trunk based development.
Most still miss on benefits TBD and CI bring.
Companies settle in the middle because git-flow is very specialized branching strategy. You almost need physically sold software (but that's still not enough!).