Is there a way to get attributes of pending devices (before accepting them)?

I’d like to be able to see the attributes (not just the public key) in order to better understand where the device is coming from and if it should actually be accepted.

When a device tries to get accepted into a fleet, it shows its identity. The device identity is a group of key=values you can define when creating/configuring the devices. I recommend taking a look at these documents to understand in a better way how device identity can be used to validate (or even pre-authenticate) your devices: