Start by trying to read data off the device from code that’s not running on Homey. For Node.js, a much-used mobile to interact with BLE devices is
However, it assumes that you already know which services and characteristics your device supports. If you don’t know that, interfacing with it may prove to be difficult. You can follow this guide on how to query a device for its services and characteristics, but if you don’t know what they do (and they’re not assigned; i.e., custom), you have to somehow interpret what they represent, and how the data is encoded.
More specifically for Homey, certain types of characteristics (NOTIFY) aren’t supported.