You found the most important stuff already.
There is a curated list about things gemini-ly here:
https://github.com/kr1sp1n/awesome-gemini
The quickstart guide may need some updating, but here it is:
Activity is listed at these two sites (but there is more)
gemini://warmedal.se/~antenna/
Creators of content contact antenna to add new links, whereas Cosmos is a crawler.