IoT with MQTT, Raspberry Pi and a cheap Remote Control
Setting up the Sonoff Tasmota MQTT Switch
Athom Homekit and MQTT WiFi Smart Relay Switch, DIY Module for Smart Home Automation, Works with Apple Homekit Siri Voice Control 10A : Amazon.de: DIY & Tools
PROFINET to MQTT Coupler | Streamline Process Management
OPC UA I/O and MQTT DAQ Module UA-7555M
MQ-7253M MQTT I/O Module with 16-ch DI (dry contact) - OKSA