Am looking to build a custom control panel with four buttons and would like to use Zigbee control. Ideally, it would be something like Fibaro's Smart Implant, but operating with Zigbee and with four contacts instead the Fibaro's two. Does something like this exist? If not, what are the best and cheapest Zigbee dry contact sensors around that I could buy 4 of?
This is really DIY and requires some different pieces to put together.
This site has firmware that you configure for various functions with a WIndows based program (same site also) and flash to TI Zigbee chips. This allows you to configure the gpios on the cc2530 for buttons, leds, sensors, relays, etc. https://ptvo.info/zigbee-switch-configurable-firmware-v2-210/
Below is the zibgee module the above firmware can be flashed to. I used these modules for a Zigbee2MQTT system and a tasmota2zigbee Hue bridge for misbehaving bulbs I purchased before I knew better. I've also configured and flashed the above firmware to one of the modules for a project I was contemplating.
CCDebugger needed to flash TI cc2530 chip.
In place of ccdebugger a nodeMCU/Wemos D1 can be used. This is the method I used as I had them on hand. Instructions for this method at site below.