Dillo can't connect to Tor or I2P through proxychains (it doesn't have its own proxy setting even), so that one is already out of the question for my usecase.

Plus darknets tend to have far more lighter hidden services/eepsites simply because both Tor and I2P users generally disable JS to increase anonymity, so the only things that require JS on there are soytes by people who just run a Tor and/or I2P mirror and never even bother using it themselves.

And browsing the darknets is going to be slower as you're passing through many computers around the world first, so you really must care about performance, and again the only ones that don't are those who just run a mirror and never even bother checking it.