3-way dimmer switch is possible using Smart Actions in the app
You don't have to wait for Kasa to release a 3-way dimmer. You can use the Smart Actions tab in your Kasa app. I replaced two traditional 3-way switches with a Kasa dimmer and a Kasa 3-way. After I installed them I was disappointed that they can't be paired by holding down the switch for 5 sec. like the 3-way instructions said. I then realized that this is a software problem. If you go into the Kasa app, click Smart Actions, press +, select "control with a switch". Then you select the first switch so that when it's on, the second switch will also be on. And set up another smart action for the reverse direction. Tada! You've got a 3-way dimmer with no waiting for Kasa to launch one!
Note: in retrospect, I may not have needed a 3-way switch, just a regular single pole since the software logic is what controls the switches, not the wires. HTH.