libtorrent implements it, so most torrent clients should have it
For BEP 39, "Updating Torrents Via Feed URL", added torrents with `info.update-url` would hit a feed to check for updates. Does qBittorrent actually do this?
For BEP 46, "Updating Torrents Via DHT Mutable Items", qBitorrent would have to allow adding torrents via magnet link with `?xs=urn:btpk:PUBKEY`. I tried this, and it didn't work. Is there some other way to do this?