Found this ESP32-C3 smartwatch (basically just comes with a demo installed) on Aliexpress for 19 euros.
Decided I wanted a temperature monitor in the case, so I put together some ESP-IDF plus LVGL code. It scrolls through different sensor data (customizable, mine has water/CPU/GPU temperature and CPU/GPU power consumption) which it pulls from the PC's LibreHardwareMonitor web server via Wifi.
Yes, the one I bought was this (I think you can find cheaper sellers as well): https://nl.aliexpress.com/item/1005006140751675.html
The code is here (though it is a bit messy): https://github.com/rosmo/CircleMonitor