Here is the curated list from Frama: https://instances.joinpeertube.org/instances that is used for the serach engine: https://sepiasearch.org/

https://diode.zone has been running many years. It was the first peertube instance I came across. Edit: https://tilvids.com/ is another

My test server you can reach at https://troll.tv/ . It has very limited federation as I need the content to pass the play store when I release an update to the android client.

Yes https://news.ycombinator.com/item?id=38444608