[pchernik]

Have you considered the "Enterprise Managed Users" feature? In my understanding this is where GitHub runs a separate instance of GitHub for you (i.e. it's not on public github.com) and one of the benefits (in my understanding) is things like globally-unique org names and such no longer applies.

[bgrainger]

That's a good point: Enterprise Managed Users does solve the globally-unique-username issue, but comes with its own list of limitations: https://docs.github.com/en/enterprise-cloud@latest/admin/ide...

We concluded it was overkill for us (but we're not primarily using github.com anyway).