Feather can be configured to route all network traffic over I2P.
Download the latest i2pd release from https://github.com/PurpleI2P/i2pd/releases
Extract the archive and run the
Go to Settings → Network → Proxy. Select i2p. Click Apply.
If “Let Feather manage this list” is checked on the Node tab, Feather should now automatically connect to an i2p node.
All other network traffic, including the websocket connection (if enabled) will also be routed over I2P.