Improving new user onboarding and community discoverability

One of the issues with joining the threadverse is that until you subscribe/join some communities, the Home feed is either very sparse (because they couldn't find the right communities) or flooded with random garbage (same reason I guess).

I'm trying a few things to help fix this.

1. I'm subscribing myself to every popular community I can find so this instance already knows about it and has content in it, making it easier for others to find.
2. Communities are grouped into a shorter list of topics. Viewing a topic shows posts from all communities in that topic, and a list of child communities in the right hand column. The viewer can drill down into a community to see a more focused subset of posts.
3. After registering a new account, new users are taken to https://piefed.social/choose_topics where they can choose some topics that look interesting. Upon clicking 'Choose', they automatically join every community in those topics. For example if they chose 'technology' they'll be subscribed to about 25 communities. If they chose a few other topics too then they could potentially find themselves part of 100 communities right after registration.

It's a good start. Eventually I'd like to incorporate something like https://lemmyverse.net/communities which knows about every community there is, without needing someone to manually add it and manually assign it a topic. Some day.