You won't regret it. A few other ideas I'm working on that I haven't found great non-homemade devices for:
Garage door controller: I have a contact sensor on the door so I can tell the state, and a relay connected to the push button so I can open and close it. I want to put a rotary encoder on the shaft so I can tell how open it is, not just closed/not fully closed, and so I can tell if it is opening or closing.
Doorbell controller: I have a dumb doorbell and prefer that to the look of the smart doorbells out there. This would allow me to intercept button pushes and also turn off the chime during nighttime/naptime and prevent rapid represses. I will also have the ability to trigger the chime. I don't know how often I'll use that, but maybe someday I'll find a use.
FastLED: This allows for some really cool LED effects with way more customization than out-of-the-box solutions. I want to have a timer in my bathroom that will countdown how much time I have left for my morning routine. It will also be fun to have a block of say four LEDs that can be set to different colours for different notifications. I have the Innovelli switches, but you can only have one colour showing at the same time. When my kids are old enough to get out of bed, I want to have a light that changes colour to let them know when they are allowed to get out of bed/out of their room.
Distance sensor: I want to integrate some ultrasonic distance sensors to check if my garbage bins have been brought to the curb/back in, and which bays in the garage have vehicles in them. This will also be used to know how far forward to park the car. Someday I want to put one of these on my front porch to notify me if there is a package sitting outside. I've thought about putting these under the bathroom sink where we store toilet paper to alert me if we are almost out of toilet paper.
Servo: I'm not sure if this is a good idea yet, but it's something to explore: A servo to control a few baffles in my ductwork to help get the right temperature in the right rooms at the right time of day.
Capacitive Touch: The ESP32 has a few capacitive touch sensors, so I want to run a think copper wire along the headboard so you don't have to be precise in the middle of the night. This would turn the whole edge of the headboard into one big button. Just whack the headboard and trigger the lights, or toggle the fan speed, or whatever.
Those are some new doors that open when you swap to using ESPs. There are also all the more common sensors that could be built for cheap with an ESPHome. Contact, vibration, motion, lux, temp/humidity, etc.
