When I was in school, most my usage for arduinos was to get/send data via serial port, through a laptop or an RPi and sending it to a server.

This kind of projects would have made my life much, much easier.

I would have loved to see a "setup" guide in your getting started page.

Hello! I'm the author of this project. The website contains a full step by step tutorial https://awot.net/en/guide/tutorial.html for deploying a standalone react app on ESP32.

Serious question: How efficient would it be to use low powered devices for a static website, rather than traditional servers?

Load balancing, and scaling (adding more micro controllers) seems like a big win.

Would the energy per request be lower of higher on the low powered devices?

Depends on the content and the amount of clients a mcu could handle at a time. For and arduino using a simple http server (no https) I think you can have up to 5 active connections before it crashes.

what WiFi module does this work with?

Any that implements the Client interface. It is not limited to WiFi modules but for example also works with Teensy and the Ethernet shield. I use it with ESP32 and ESP8266 most of the time.