I have an Amazon FireTV and one day, when I had my work Windows PC at home, it could stream via Bluetooth (like an external screen). There was lag when starting

I have an Amazon FireTV and one day, when I had my work Windows PC at home, it could stream via Bluetooth (like an external screen). There was lag when starting / changing videos, but otherwise it seemed to work well enough. Don't most smart TVs have Bluetooth today? In my case, the FireTV is plugged into my (dumb) PC monitor.