As others mentioned, running a minecraft server by itself is pretty easy. If you want additional features like a Web UI, multiple servers at the same time etc. you might take a look at Crafty Controller.

This, but Forgejo instead of Gitea.

https://github.com/andyholmes/valent/

It’s the other way around. 0.1 kWh means 0.1 kW times 1 h. So if your device draws 0.1 kW (100 W) of power for an hour, it consumes 0.1 kWh of energy. If your device factory draws 360 000 W for a second, it consumes the same amount of 0.1 kWh of energy.

I’m likely to rebuild the backend in Go

Why bother with another language? Rust offers multiple great backend options. Using the same language for both ends might allow reusing some parts.