These Aqara wifi buttons can be found for around 10 EUR each on amazon from time to time. Ikea TRADFRI switches are even cheaper and also supported as long as you don’t go with the updated ikea hub since that one isn’t compatible with HA just yet. Similar story for Aqara hubs (also similar versions) so no need to get any of those. Instead I’ll explain how you can get these zigbee switches working on your local network using a simple USB zigbee adapter on your Raspberry Pi.
So yes you’ll need an usb dongle on your Raspberry Pi to enable it to use integrations like zigbee2Mqtt. You can find these adapters as a direct GPIO add on for your RPi or as an USB dongle. The benefit of the USB dongle is that you can use USB extension cords (max 3m according to USB spec) and that it also works with USB other devices.
Some steps to get this working for these AQARA sensors are described here but honestly the procedure is fairly simple. You just need to set up that ZigBee dongle once by plugging it in the USB port and rebooting the Pi. At that point it was ready to configure in HA settings. You can pick “create new network” or “restore from backup”. That last option sounds great if you had a network in the past with a ton of sensors already paired.
Once that is done you can add zigbee supported devices with the “add device” option picking SONOFF Zigbee device type. The devices itself you can put in pairing mode by long pressing the button on them. Don’t forget to pull the battery tab when using them for the first time.
And honestly that’s about it. When I ordered my AQARA switches on amazon they delivered a temperature sensors and a vibration sensor instead. Not sure how or why but that means I’ll keep those and integrate these also. I mostly need actual switches though to trigger my garage doors. So I’ll pass by Ikea next to get those TRADFRI ones.