Python client for the $20 Colmi R02 smart ring

So you just scan for devices and then read? There's no authorization involved, these just publish the readings wirelessly for all interested?

The ring has a very minimal interface. Apart from the sensors - an accelerometer to count steps and two LEDs with photodiode to get heart rate and blood oxygen - there is one status LED on the inside to indicating charging. That's it. The ring is a pure data collection device that basically can't be interacted with without the app.

Maybe they could have required you to hit the ring on a surface to initiate pairing mode. But as it stands the ring will pair with any device that asks for it.

I'm looking forward to someone making a custom firmware for these rings. There is some work in the linked ATC_RF03 project, but I'm not sure if anyone is still working on it