Fluke Networks 26000900 Pro3000 Tone Generator and Probe Kit with SmartTone Technology

You could do this with Shellys, or you could just replace the switches with decora-style smart paddles. Your landlord might or might not notice that. It's probably easier than Shellys. If the overhead lights are not already on a dimmer, the fixtures may not be dimmable. Try and see though, in some places it's required by code for all fixtures to be dimmable. For the 3-way paddles as long as you put the Shelly in the box closest to the load it's easy to wire up. The load goes into the Shelly and the 3-way switches also go into the Shelly. You'll change what the traveler wire means, but it's all easy to put back when you leave. Get yourself a tone and probe kit so you can easily tell which wire is which. https://www.amazon.com/dp/B000FTADX0 Also get yourself a noncontact voltage tester. A cheap one will do, but some boxes may have voltage from other breakers in them, you want to know before you short something. https://www.amazon.com/dp/B099SJ6469/ Make sure you buy the UL rated Shellys. They sell non-UL ones. As others have said, use wago lever locks (get the real ones don't cheap out) they make everything easier. Get yourself a homeassistant install, you're going to love it.