Thankfully GitHub has an easy web-based Pull Request process. It's not as simple as a custom UI, but could be used by non-engineers to change flags.
That's a licensing thing, not a feature flag.
But there's also a surprisingly common situation with big customers who want to limit and control certain UI updates so they can ensure that employees are trained appropriately.
But it's all the same code under the covers. The functionality of what is enabled encoded into a license key - that's the same type of functionality as "does this deployment allow people to sign up by email" or "has this deployment enabled the super secret power user test functionality?"
But that's all under "if dataSource.toggle then {something}"