Stolen MacBook Air still showing under my devices. Does it mean it hasn't been reset yet?

My Macbook was stolen and I was wondering as long as it’s still in your devices, does it mean they didn’t reset it yet? And what if they use your computer for selling the different parts, is there a way to find this out? I reported it to the police but I’m not sure if I should erase everything in case they can find it back so I don’t lose everything. It was last online yesterday morning so I haven’t lost all of my hope yet. 🤷🏽‍♀️

[Re-Titled by Moderator]