ESPHome release 2021.8.0, just released, includes my PR to directly support the TSL2591 sensor. My previous waterbug.yaml depended on loading support as a custom component, along with the Adafruit TSL2591 library. The ESPHome support uses the ESPHome I2C abstraction and does not use the Adafruit TSL2591 library at all. A nice side-effect of that is no longer needing to configure a fake "spi:" entry because of the Adafruit standard sensor library's dependency.

Changes to waterbug.yaml to use the ESPHome support for TSL2591 are minimal and are mostly removing things. I updated the YAML files on this project to reflect the changes.