Any support outside of qbitorrent yet? I know it's not FOSS, but I much prefer working in Tixati. Do I need to refamiliarize myself with qbitorrent if I want to try i2p?
Try BiglyBT (or i2psnark, the built-in torrent client). Those two have been the standard I2P torrent clients long before qBittorrent began adding support.
For any other torrent clients you'll need to request that those devs work on adding I2P support. e.g. for Tixati I guess you can start by asking about that in their forums https://forum.tixati.com/
PS - Not I2P or torrents related, but since you prefer Tixati you may want to see DarkMX it is a file sharing client that runs over Tor developed by the same person that also created Tixati / WinMX / Fopnu. (I've never used it myself)