You're probably going to have a hard time finding consumer networked light switches that run on anything that isn't a wireless protocol. It's been a minute since I did any of this kind of work, but as I recall it, most US building codes forbid high-voltage (for residential values of the term, meaning ~120V wall supply) and low-voltage cabling from being run in the same conduits or boxes. That makes Ethernet and any other wired protocol (that isn't powerline) impossible, at least unless you're OK with risking your network cabling becoming live at mains voltage, and/or not getting a payout from your fire insurer if your house ever burns down.
Except, doesn't require a custom android/ios app. I do want wireless protocol, but once the switch is networked, I want to be able to control it without some middle-man app that is phoning home outside of my network.
And Ikea will release zigbee wall plugs this year, their gateway uses the open coap protocol (no need to use their app) and as said you can also use any zigbee controller you want.
Fibaro sells zwave wall plugs, but there are others.
Finally sonoff has wifi plugs which can be flashed with open firmware.
Problems with it:
- doesn’t work across phases, but I believe there is a ‘bridge’ for that.
- noise ie from switching power supplies on the lines can be a problem. Use filters / better supplies.
In any case, good luck!