As I was trying to find a useful (and free) list of Discourse forums online and since I couldn’t find one, I went ahead and created a crowd-curated “awesome” list on GitHub anyone can contribute to: awesome-discourse-communities/README.md at main · rugpullindex/awesome-discourse-communities · GitHub
My hope is that over the many years to come, a few searchers will end up here, find my repository and help contribute with links.