The shape of this HN duplicate detector actually works as a GitHub uptime chart:

https://news.ycombinator.com/from?site=githubstatus.com

It's driven by aggregated user complaints, so it's pretty high-quality. Comment counts are a proxy for "how bad was the outage" + "how long was the outage thread topical for".

edit to add: Here's a scatterplot of the same,

https://files.catbox.moe/hhfh4l.png