How can I toggle two wall sconces, without also turning off power to receptacles?
First off, I would get approval from your landlord before making any wiring changes to your apartment. You never know, he might be friendly enough that he would hire an electrician to make the changes you want.

I would first attempt to figure out how the receptacles are wired to the switch. If there is a way to separate them, then I would do that.

If not, then I would bypass the switch and just make everything permanently on. then just use your wireless bulbs and remote app. You should be able to replace the switch with the wireless switch, but make sure it works with your bulbs.