Dear Lord yes, that is FUN! I'd love to see 'walk up music' like in MLB, but for anyone and changing randomly from time to time.
I am looking to make my house more reactive as well. One area where HA has been a godsend was integration with TV/Music/idle off. Whereas there wasn't one solution which would shut off the TV and stereo in my set up once they were in Harmony Hub I could add idle timeouts for them in HA.
Another was theater lighting when the TV starts. In the theme of ambience I am looking at switching the lights to something more colorful when paused.
* Raspberry Pi (I've since moved to a Ubuntu server, but Pi was perfectly capable on this entire setup)
* Aeotech Z-wave z-stick (for controlling the wireless sensors)
* Lots of z-wave sensors (door, motion, temperature, humidity, flood, one that listens for my smoke alarms going off, a whole house power sensor in the circuit breaker box, ...)
* Lots of z-wave switches (some where I replaced light switches with smart switches, others where I just piggied a z-wave relay between the wall and the thing)
* A few Phillips HUE lights for fun color BS
* an old 433 MHz temperature sensor that the previous tenant left without the weather station (read through a $5 USB TV receiver)
* Another Raspberry pi sitting on my stereo hooked to Snapcast to pipe synchronized wifi audio throughout the house from a single source.
* Mopidy as the central music server to pipe stuff through Snapcast
* OpenWRT router running some scripts for presence detection
* Cellphones via web interface for control
* Also a fun little LED dot-matrix display for fun displays
* A few Amcrest IP cameras (with cloud crap disabled)
Software is very Home Assistant heavy, with lots of little auxiliary scripts, some home-built, many others from other enthusiasts. The central community is the Home Assistant crew. But also:
* MQTT on a remote MQTT broker ($5 VPS) for communicating with external devices (like my mom's house and my cellphone when off-site)
* Owntracks for GPS-driven automations
* Self-hosted e-mail (totally unnecessary, just a hobby)
I think that's about it.
For getting started, yeah just start small. Get a z-wave usb stick and a pi and a few little sensors. Hook it up to your stereo and wifi and start fiddling based on the examples from home-assistants forum and docs. Then it just slowly bootstraps up to something elaborate, if you're enjoying it.
The "Wail" recording here, in particular: https://www.syracuse.com/indepth/2008/07/audio_hear_the_call...
Once it was all set up it just runs itself with little tweaks and additions one a month.
I used Home Assistant to graph my pool temp, and control my pump so that I made most use out of our solar heaters.
As for Doorbell, it's pretty much like this: https://partofthething.com/thoughts/making-my-analog-doorbel...
* Self-hosted security system that e-mails me when triggered. It arms when everyone disconnects from the wifi and disarms when anyone in the home reconnects to wifi. Totally passive. Also arms at night when the kitchen lights have been out for 5 minutes after a certain time and disarms when motion patterns that can only be someone waking up are sensed.
* E-mails work and personal when smoke alarm goes off or when water is detected in basement
* E-mails pic from front door camera when doorbell pressed (yeah, like Ring, but with a ESP8266 monitoring my normal doorbell)
* Voice reminder on garbage day
* Northern loon call exactly at each sunset
* Ambient jungle noises and lights on when I wake up and it sees me
* Laundry timer + reminders
* Vacation mode random lights on/off
* Plays a Ship's bell chime on the hour, but only during daytime (ambiance)
* Tones when any outside door in the house opens. Optionally: random Seinfeld bass transitions
* Alert for power outage
* Alert if my mom's house temperature goes too low in winter when she's away (I've called the plumber to fix the furnace thanks to this)
* Turn on A/C if temperature above threshold at 4:00pm in anticipation of my return from work
Stuff like that. Loads of fun. Lots of fiddling.