I didn't end up using mine, as walking while keeping both hands on the keyboard doesn't work the right places in my back. I also get really sweaty when walking indoors with no breeze, it turns out.
I'd recommend a cheap second-hand treadmill if you're going to try -- people are always selling these after shelling out a heap of money and realising that they mainly collect dust.
Well if you're looking for a real use, I ask a local LLM the setup for a child's joke several times a day, and post its answer to my tens of Mastodon followers: https://botsin.space/@jokeunderstander
I'm so grateful for what Home Assistant has done for home automation and compatibility, but its focus on dashboards and phone interfaces seems to lead everyone who uses it in exactly the wrong direction.
I don't think it's a coincidence that a lot of what you like about 'Home Assistant' is Node-RED and Zigbee. They are two of the big building blocks for making a home that is more convenient to live in rather than less (the third being an MQTT server.)
I built Joke-Understander bot, a Mastodon bot that responds to a joke setup before the punchline is revealed. It's not very popular but I think it's hilarious.
I built a mental health tracker and a physical health tracker, that sit in my living room and use LEDs to display a prediction of how good my health is.
The mental health tracker keeps track of my sleep, and how long it takes me to do various things in the morning. The physical tracker keeps track of how much walking I'm doing and how often I'm doing certain exercises.
They have slightly different uses; with mental health I only really notice whether I'm feeling 'okay' or 'extremely bad', so seeing a far more granular estimate is useful. The physical health is more a reminder that it's time to do certain exercises to keep the back pain at bay for a bit longer.