I'm curious what sources people are using as well. I use reddit, hackernews, and a ton of slack channels (how I miss IRC).
For RSS specifically, the folks at @Framasoft are doing great work creating and supporting opensource services/software.
They have a hosted "Framanews", or you can download and host it yourself.
Fosstodon is an English speaking Mastodon instance that is open to anyone who is interested in technology; particularly free & open source software.