For my own morbid curiosity, why Zigbee?
If you don't want to learn ESP Home yet, but you're ok with Wifi, here's a sensor that uses ESPHome, but is all pre-programmed and ready to go with Home Assistant. I haven't used this produce yet, but the other products from Apollo are pretty awesome.
https://apolloautomation.com/products/temp-1-temperature-probe-for-home-assistant
Not saying you're wrong, but I'm married and I never wear my wedding band unless its a special occasion. I know too many people that lost a finger because of it. My wife doesn't care and I'm just used to not wearing it. People still seem to figure out that we're married.
It came with a plug in wireless chime, but nothing to wire to the old chimes. I have only been using it since October, but no issues so far. We live in the country, so not a lot of visitors either, but we have had several people use it over the holidays.
This is the exact one I purchased: https://a.co/d/88peOTU
I'm powering it with this: https://a.co/d/dpTUHh4
Mine is connected to the network wirelessly. It is powered from the doorbell transformer.
I have a Reolink Doorbell. We have about the simplest/cheapest mechanical chimes you can get. (2 total, one on each floor). The Reolink said I should disconnect the chimes and use their electronic ones, because it might mess up the doorbell if I didn't. I ignored this advice, and the Reolink still rings the mechanical chimes when somebody presses the button. I have yet to see any issues with the Reolink. I did plug in their wireless chime also, and it rings too.
So I would say, YMMV, but there's a good chance a Reolink will still ring your chimes.
You'll want to research "room presence" systems.
Here's one I've been looking at implementing for an example: https://espresense.com/
NTFY Any reason to pick NTFY over Gotify? I've been using Gotify for quite a while with good luck, but I would switch if there was a compelling reason.
"I'm never moving it again...". As a larger guy that owns a pickup truck, I wish I had a nickel for everytime I heard that about a big rack I help move. (Or a baby grand piano, pool table, or gun safe) :)
I have installed 3 of these now. A little expensive for an outright cost, but well worth it when you see how easily it integrates with the garage door openers. You can a ton of information out of it and some other goodies like parking sensors. They did a great job of making it really easy to install and straight forward to add to Home Assistant. You save a ton of money in the long run over a MyQ subscription.
I use the M5Stack C124 AtomS3 Lite with the RS485 Base for direct local control of my Rheem water heater. (I have the heat pump version, but it works with other versions also)
https://github.com/esphome-econet/esphome-econet
Way better than using the econet integration in home assistant. It eliminates the need for the Econet account and cloud. Now it is all local and provides way more information and options than the built in integration.
I know it isn't technically a stand alone project made by a specific company, but it was so easy to install and setup and really pretty cheap. No soldering and just some very minor modifications to an existing phone cable that I sacrificed to the cause.
My server uses about 6-7 kWh a day, but its a dual CPU Xeon running quite a few dockers. Probably the thing that keeps it busiest is being a file server for our family and a Plex server for my extended family (So a lot of the CPU usage is likely transcodes).
Similar idea, but a different service if you like gotify: https://github.com/tystuyfzand/gotify-smtp