Well going all in on GitHub / GitHub Actions now really sounds like a bad idea. Even some others had issues [0] and had no external backup plan to counter GitHub's regular outages.
The best example to learn from is ReactOS who while has moved to GitHub they at least have a self-hosted backup just in case GitHub falls over. [1]
For the ones who are not on GitHub and are self-hosting (OpenBSD, Mozilla, Linux Kernel Project, GNOME, xfce, wireguard) I don't hear any complaints from them.