If you want to know what files are being shared, there are some indexing apps for selfhosting that can scan the peers of a tracker (though DHT crawling is probably the better solution)

Uhh. Your torrent client will automatically handle querying them and finding what you're looking for (peers).

op is very obviously asking how to find out which files are being shared rather than finding peers

I’m talking about creating new torrents, not finding existing ones.

I suppose another use case is when you found a rare torrent which no longer works (no seeds, trackers down, etc), you might be able to get it to work this way. My question is: anyone got success stories with this use case?