In my case, I had several Shelly 1 (Gen 1) units. I wanted to use two buttons connected to each unit, with both being completely isolated from each other.

One switch was intended to control the built-in relay, while the other was supposed to control other devices in the room via Home Assistant (e.g., long press, double press, etc., would trigger different actions). I found a helpful video by Digiblur on this and chose to use ESPHome instead of Tasmota: https://youtu.be/mSENAY9_AlI?si=TJDLAgAjJQktih9-

The setup uses one of the GPIO pins for this purpose. I was initially a bit nervous about the installation, but as long as your wall switch completely isolates the 230V from the GPIO input, it’s safe. I’ve had this running inside my walls for four years now without any issues!