Migrating off of GitHub once established is very hard in practice. That is why so many projects have stayed there. But asking people to make a Microsoft GitHub account when your Goal 1. is 'Independent' starts the project off with not following its own goals.
People might be hesitant to open an account at the hoster of the aux.computer infrastructure, so aux.computer could offer the option of logging in with a Microsoft GitHub account.
The Linux kernel, GNOME, KDE, Debian, Blender and more host they own forge. It's not a very heavy service. Running aux.computer infrastructure on aux.computer OS is a good showcase of the project.