Please, share your thoughts and ideas for what purposes, you use smart button with Home Assistant?
I have a Logitech Pop button at my Sonos One.
One push will ungroup the Sonos and start playing a specific radio station.
Double push will do the same, but for another radio station.
Long press will ungroup and play a Top50 playlist from Spotify.
The ungrouping is to avoid waking up the kids in the morning, if the Sonos’ were grouped from last night.
They each have a Sonos in their rooms.
I have an automation that reminds me to take my medicine at the appropriate time. HA nags me with a verbal message until the dash button is pressed.
I am currently working on a 2nd automation to remind me to buy softener salt. I press a Dash Button when I add a bag and HA counts the number of recycles based on electric usage. When recycle count exceeds 10, I get notified.
Wifi plug on the coffee machine.
In the morning, pressing the dash button the plug goes on and I have hot coffee!
BUT I have only 15 minutes!! 
My partner keeps one in her pocket when she goes out to do gardening and other yard piddling. If she needs me or if bees attack, she presses her pocket button to have my office light flash and Alexa speak up saying she wants me for something. It’s got a reliable range of 140’ from the router so most of the yard is covered.
We also have one hanging in the carport that will turn on selected lights in the homestead for when we come home to a dark house and paranoid.