Start with an npub that has a large follow list. Query its follow list (Kind 3), and for each pubkey in the list, query its Relay List Metadata (Kind 10002). Then, recursively repeat this for followers of followers, and if you're brave enough, go for level 3 as well. As you traverse the graph, store all relays from Kind 10002 in a set. You’ll end up with well over 1,000 entries in this set. Although you’ll find a lot (and I mean a lot) of junk. Clean up the URLs, test the relays, and Bob's your uncle.
Discussion
Yep, that's basically what we are doing. You can start with the users own relays. You can also use relay hints from all events to get more relays to check. Then you need to send the onion addresses via Tor and remove the local relays. Then download everybody's list and store to assemble the feeds.
Cool. Thanks 🙏