I Designed My Own Home Control Handset
Rather than buying a controller, I designed one: my own circuit board with an ESP32, a small programmable chip with built-in wireless, running the free ESPHome firmware.
That combination lets the remote talk to Home Assistant, so one device can switch lights or adjust the heating without opening an app.
I go through the whole path, from drawing the circuit board to getting the chip programmed and the buttons doing what they should.