I just downloaded and have been loving this. It loads pretty quickly, navigation is intuitive, and I'll finally stop forgetting that Nebula exists because it'll all be in my one big subscription feed.
Since I'm new to moving over to open source, I want to ask the veterans: is this as incredible as it seems right now, or is there something I'm missing?
They encourage you to contribute to the project and add plug-ins, they are just making sure your modification does not become the defacto so they can make sure malware, trackers or ads are not implemented into the application. They have the right to go after you if you go against this but sharing a modified apk with a friend is not going to revoke your license or get you targeted.
We can fight if that's the right approach but it's certainly not open source, just source available!