Im using a Hubitat C7 for a radio, and Home Assistant running on an old Dell SFF computer (cheaper than buying a raspberry pi4, while being faster).
Currently at 22 devices,
15 Switches, 13 are Inovellis, 2 Zooz
2 Iris contact sensors and 1 Iris motion sensor, these 3 are Battery powered Zigbee.
And then a Zwave tilt sensor on the garage, and a Zooz relay for controlling the garage door.
Contact sensors on my pantry door and my closet door because I always forget to turn the light off on those.
Motion sensor is in my laundry room, because my cats litter box is in there. It triggers the exhaust fan to run for 5 minutes.