Hey there! I responded already in the corresponding GitHub issue, but just to re-iterate:
- Sending private messages is currently not implemented in Thunder but will likely be available in the next update v0.9.0 (currently work-in-progress)
- Following users is not implemented in Lemmy so that likely won't come to Thunder anytime soon. However, it looks like Lemmy will have the ability to follow posts in their v1.0.0 release so that may come once that's released!
Hope that clarifies your questions!