Configure your smart switch module to work with Tasmota open source firmware.
What's so special about Shelly Plus (Shelly 1/1PM/2PM/i4/WS Plus) - NotEnoughTech
Push Button on Shelly Devices · Issue #4914 · arendst/Tasmota · GitHub
ESP32 Based Devices
Shelly Plus 1 flashing and setup guide/ tutorial - ESPHome - Home Assistant Community
Shelly stock firmware v1.1.0 prevents to install Tasmota · Issue #31 · tasmota/mgos32-to-tasmota32 · GitHub
Shelly 1 - Tasmota
Shelly Plus AddOn support · Issue #1146 · mongoose-os-apps/shelly-homekit · GitHub
Shelly EM Switch Module Configuration for Tasmota
Adding Shelly Plus 1PM · Issue #61 · yaourdt/mgos-to-tasmota · GitHub
Shelly Plus Plug S - Computer & Techniek
AU Devices
Shelly Plus 1 Switch Module (SNSW-001X16EU) Configuration for Tasmota
RevK®'s ramblings: Shelly Plus 1 GPIO
EU Devices