I got myself an ESP32 with an integrated e-ink display. This little project shows when the next bus to the city leaves, and the current time. I get the live bus data from Skyss through the Entur integration in Home Assistant. Might have to get a few more of these to tinker with.
A while back I made a Lolin32-based weather station that lasts for around 60 days on a single disposable vape battery.
It wakes up every 15 mins, and while it's connecting to WiFi it retrieves the AM2302 sensor readings. As soon as they're transmitted it goes back to sleep.
I wish there was a more power efficient alternative though, like whatever is being used in those BLE LYWSD03MMC sensors that last for around 3-6 months on a cr2032 whilst also having a display built in