@i2p
I use the InviZible Pro app to access i2p on Android. The problem with that for some of these browsers is they only allow using the i2p setting via the Purple i2p app. This forces me to use custom/manual, port 4444.

On a side note, there's a bug in the Lightning browser where it forgets to use a custom proxy after closing; it remembers the setting, just forgets to use it. I just have to open the manual port setting at each start, then OK out of the menu and it works again.