An open source PCB for home automation that hosts an ESP32 chip, powers it via mains and gives access to 4 dry-contact relays, 8 GPIOs and the I2C bus.
Full PCB documentation and gerber files available on Upverter (see external links).
The board works flawlessly with ESPHome (and, hence, Home Assistant).
As a bonus, I've also developed an enclosure, available on Tinkercad (see external links). The enclosure is meant to provide easier, but not IPXX-rated handling of the PCB when powered on; it's still recommended to store the device inside an insulated electrical box.
Current version is 1.0.1. Pictures show v1.0, which is basically the same, except a few minor details have been improved in v1.0.1 (changelog at Upverter).