Take a look at https://fediverser.network/?mapped=true, and it will tell you exactly what are the recommended alternatives to any subreddit. This is a crowdsourced database, anyone can signup and make a recommendation, which I then can merge into the list.

So in theory, we could facilitate the migration of users in mass if the clients did two things:

• provided a "login via reddit" system (like the one on https://portal.alien.top)
• Use the data from the fediverser database to auto-subscribe the logged user with their list of subreddits (which could be obtained when they authenticate with reddit)

This would single handedly solve all the "content discovery" issues, and if more instances beyond alien.top integrate with fediverser, we could even have a system that selects an instance to user automatically.