Great article. I'd like to add a bunch of smart switches during a remodel, but don't understand why the legacy form factor (toggle) is all but missing from product offerings today. Insteon makes one that's been very reliable for me. The 2466SW is a three position (momentary up and down from center for on and off), but it only works with Insteon. Haven't seen anything similar for Alexa, Siri, or Google.
Found there is another consideration - Whether switch can be installed in a 2-, 3- or 4-gang box. I was going to replace only the Right-side switch with WiFi one in a 2-gang box, but cover plate (this was a KMC dual) not compatible with leaving a standard toggle on the left position, I would've had to change BOTH to WiFi.
Might want to consider Lutron Caseta will do up to 60 switches off of one Hub they arent super expensive, they look good offer Sonos controls for music playback etc... And are also voice controllable if setup properly... Also have dimmer switches and remote controllsfor 3 way switches etc...
Are there any options yet to eliminate wall switches entirely? It seems like a tiny inline component wired at the fixture could be easily done by now. Saving all that extra wire, boxes, and components would seem to offset much of the cost. I suspect that offset would go a long way toward countering people's need for the security blanket of a manual switch they can touch.